Averages/Arithmetic mean: Difference between revisions
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{{task|Probability and statistics}}
;Task
Write a program to find the [[wp:arithmetic mean|mean]] (arithmetic average) of a numeric vector.
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=={{header|0815}}==
<syntaxhighlight lang="0815">
{x{+=<:2:x/%<:d:~$<:01:~><:02:~><:03:~><:04:~><:05:~><:06:~><:07:~><:08:
~><:09:~><:0a:~><:0b:~><:0c:~><:0d:~><:0e:~><:0f:~><:10:~><:11:~><:12:~>
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=={{header|11l}}==
{{trans|Python}}
<syntaxhighlight lang="11l">F average(x)
R sum(x) / Float(x.len)
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=={{header|360 Assembly}}==
Compact and functional.
<syntaxhighlight lang="360asm">AVGP CSECT
USING AVGP,12
LR 12,15
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Called as a subroutine (i.e., JSR ArithmeticMean), this calculates the integer average of up to 255 8-bit unsigned integers. The address of the beginning of the list of integers is in the memory location ArrayPtr and the number of integers is in the memory location NumberInts. The arithmetic mean is returned in the memory location ArithMean.
<syntaxhighlight lang="6502asm">ArithmeticMean: PHA
TYA
PHA ;push accumulator and Y register onto stack
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=={{header|8th}}==
<syntaxhighlight lang="forth">
: avg \ a -- avg(a)
dup ' n:+ 0 a:reduce
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=={{header|ACL2}}==
<syntaxhighlight lang=
(if (endp xs)
(mv 0 0)
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=={{header|Action!}}==
{{libheader|Action! Tool Kit}}
<syntaxhighlight lang=
PROC Mean(INT ARRAY a INT count REAL POINTER result)
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=={{header|ActionScript}}==
<syntaxhighlight lang=
{
var sum:Number = 0;
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=={{header|Ada}}==
This example shows how to pass a zero length vector as well as a larger vector. With Ada 2012 it is possible to check that pre conditions are satisfied (otherwise an exception is thrown). So we check that the length is not zero.
<syntaxhighlight lang="ada">with Ada.Float_Text_Io; use Ada.Float_Text_Io;
with Ada.Text_IO; use Ada.Text_IO;
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=={{header|Aime}}==
<syntaxhighlight lang="aime">real
mean(list l)
{
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{{works with|ALGOL 68G|Any - tested with release mk15-0.8b.fc9.i386}}
{{works with|ELLA ALGOL 68|Any (with appropriate job cards) - tested with release 1.8.8d.fc9.i386 - note that some necessary LONG REAL operators are missing from ELLA's library.}}
<syntaxhighlight lang="algol68">PROC mean = (REF[]REAL p)REAL:
# Calculates the mean of qty REALs beginning at p. #
IF LWB p > UPB p THEN 0.0
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=={{header|ALGOL W}}==
<syntaxhighlight lang="algolw">begin
% procedure to find the mean of the elements of a vector. %
% As the procedure can't find the bounds of the array for itself, %
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Because of the way Amiga E handles floating point numbers, the passed list/vector must contain
all explicitly floating point values (e.g., you need to write "1.0", not "1")
<syntaxhighlight lang="amigae">PROC mean(l:PTR TO LONG)
DEF m, i, ll
ll := ListLen(l)
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=={{header|AntLang}}==
AntLang has a built-in avg function.
<syntaxhighlight lang=
=={{header|APL}}==
{{works with|APL2}}
<syntaxhighlight lang="apl"> X←3 1 4 1 5 9
(+/X)÷⍴X
3.833333333</syntaxhighlight>
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With vanilla AppleScript, the process is the literal one of adding the numbers and dividing by the list length. It naturally returns results of class real, but it would be simple to return integer-representable results as integers if required.
<syntaxhighlight lang="applescript">on average(listOfNumbers)
set len to (count listOfNumbers)
if (len is 0) then return missing value
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The vanilla method above is the more efficient with lists of up to around 100 numbers. But for longer lists, using Foundation methods with AppleScriptObjectC can be useful
<syntaxhighlight lang="applescript">use AppleScript version "2.4" -- OS X 10.10 (Yosemite) or later
use framework "Foundation"
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=={{header|Applesoft BASIC}}==
<syntaxhighlight lang=
0 READ V$
1 IF LEN(V$) = 0 THEN END
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=={{header|Arturo}}==
<syntaxhighlight lang="rebol">arr: [1 2 3 4 5 6 7]
print average arr</syntaxhighlight>
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=={{header|Astro}}==
<syntaxhighlight lang="astro">mean([1, 2, 3])
mean(1..10)
mean([])
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=={{header|AutoHotkey}}==
<syntaxhighlight lang="autohotkey">i = 10
Loop, % i {
Random, v, -3.141592, 3.141592
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=={{header|AWK}}==
<syntaxhighlight lang="awk">cat mean.awk
#!/usr/local/bin/gawk -f
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=={{header|Babel}}==
<syntaxhighlight lang="babel">(3 24 18 427 483 49 14 4294 2 41) dup len <- sum ! -> / itod <<</syntaxhighlight>
{{Out}}
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Assume the numbers are in an array named "nums".
<syntaxhighlight lang="qbasic">mean = 0
sum = 0;
FOR i = LBOUND(nums) TO UBOUND(nums)
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To calculate the mean of an array:
<syntaxhighlight lang=
REM specific functions for the array/vector types
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==={{header|IS-BASIC}}===
<syntaxhighlight lang=
110 LET ARR(3)=3:LET ARR(4)=1:LET ARR(5)=4:LET ARR(6)=1:LET ARR(7)=5:LET ARR(8)=9
120 PRINT AM(ARR)
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=={{header|bc}}==
Uses the current scale for calculating the mean.
<syntaxhighlight lang="bc">define m(a[], n) {
auto i, s
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=={{header|Befunge}}==
The first input is the length of the vector. If a length of 0 is entered, the result is equal to <code>0/0</code>.
<syntaxhighlight lang="befunge">&:0\:!v!:-1<
@./\$_\&+\^</syntaxhighlight>
=={{header|blz}}==
<syntaxhighlight lang="blz">
:mean(vec)
vec.fold_left(0, (x, y -> x + y)) / vec.length()
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=={{header|Bracmat}}==
Here are two solutions. The first uses a while loop, the second scans the input by backtracking.
<syntaxhighlight lang="bracmat">
(mean1=
sum length n
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</syntaxhighlight>
To test with a list of all numbers 1 .. 999999:
<syntaxhighlight lang="bracmat">
( :?test
& 1000000:?Length
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=={{header|Brat}}==
<syntaxhighlight lang="brat">mean = { list |
true? list.empty?, 0, { list.reduce(0, :+) / list.length }
}
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=={{header|Burlesque}}==
<syntaxhighlight lang="burlesque">
blsq ) {1 2 2.718 3 3.142}av
2.372
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Defines a tacit Avg function which works on any simple numeric list.
<syntaxhighlight lang="bqn">Avg ← +´÷≠
Avg 1‿2‿3‿4</syntaxhighlight>
<syntaxhighlight lang="text">2.5</syntaxhighlight>
[https://mlochbaum.github.io/BQN/try.html#code=QXZnIOKGkCArwrTDt+KJoAoKQXZnIDHigL8y4oC/M+KAvzQ= Try It!]
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Compute mean of a <code>double</code> array of given length. If length is zero, does whatever <code>0.0/0</code> does (usually means returning <code>NaN</code>).
<syntaxhighlight lang="c">#include <stdio.h>
double mean(double *v, int len)
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=={{header|C sharp|C#}}==
<syntaxhighlight lang="csharp">using System;
using System.Linq;
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Alternative version (not using the built-in function):
<syntaxhighlight lang="csharp">using System;
class Program
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=={{header|C++}}==
{{libheader|STL}}
<syntaxhighlight lang="cpp">#include <vector>
double mean(const std::vector<double>& numbers)
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Shorter (and more idiomatic) version:
<syntaxhighlight lang="cpp">#include <vector>
#include <algorithm>
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Idiomatic version templated on any kind of iterator:
<syntaxhighlight lang="cpp">#include <iterator>
#include <algorithm>
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=={{header|Chef}}==
<syntaxhighlight lang=
Chef has no way to detect EOF, so rather than interpreting
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Returns a [http://clojure.org/data_structures ratio]:
<syntaxhighlight lang="lisp">(defn mean [sq]
(if (empty? sq)
0
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Returns a float:
<syntaxhighlight lang="lisp">(defn mean [sq]
(if (empty? sq)
0
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=={{header|COBOL}}==
Intrinsic function:
<syntaxhighlight lang="cobol">FUNCTION MEAN(some-table (ALL))</syntaxhighlight>
Sample implementation:
<syntaxhighlight lang="cobol"> IDENTIFICATION DIVISION.
PROGRAM-ID. find-mean.
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=={{header|Cobra}}==
<syntaxhighlight lang="cobra">
class Rosetta
def mean(ns as List<of number>) as number
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=={{header|CoffeeScript}}==
<syntaxhighlight lang="coffeescript">
mean = (array) ->
return 0 if array.length is 0
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'''With Reduce'''
<syntaxhighlight lang="lisp">(defun mean (&rest sequence)
(when sequence
(/ (reduce #'+ sequence) (length sequence))))</syntaxhighlight>
'''With Loop'''
<syntaxhighlight lang="lisp">(defun mean (list)
(when list
(/ (loop for i in list sum i)
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=={{header|Crystal}}==
<syntaxhighlight lang="ruby"># Crystal will return NaN if an empty array is passed
def mean(arr) : Float64
arr.sum / arr.size.to_f
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=={{header|D}}==
===Imperative Version===
<syntaxhighlight lang="d">real mean(Range)(Range r) pure nothrow @nogc {
real sum = 0.0;
int count;
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mean: 3.83333</pre>
===More Functional Version===
<syntaxhighlight lang="d">import std.stdio, std.algorithm, std.range;
real mean(Range)(Range r) pure nothrow @nogc {
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===More Precise Version===
A (naive?) version that tries to minimize precision loss (but already the sum algorithm applied to a random access range of floating point values uses a more precise summing strategy):
<syntaxhighlight lang="d">import std.stdio, std.conv, std.algorithm, std.math, std.traits;
CommonType!(T, real) mean(T)(T[] n ...) if (isNumeric!T) {
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=={{header|Dart}}==
<syntaxhighlight lang="d">num mean(List<num> l) => l.reduce((num p, num n) => p + n) / l.length;
void main(){
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This is not a translation of the bc solution. Array handling would add some complexity. This one-liner is similar to the K solution.
<syntaxhighlight lang="dc">1 2 3 5 7 zsn1k[+z1<+]ds+xln/p
3.6</syntaxhighlight>
An expanded example, identifying an empty sample set, could be created as a file, e.g., amean.cd:
<syntaxhighlight lang="dc">[[Nada Mean: ]Ppq]sq
zd0=qsn [stack length = n]sz
1k [precision can be altered]sz
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By saving the sample set "1 2 3 5 7" in a file (sample.dc), the routine, listing summary information, could be called in a command line:
<syntaxhighlight lang="dc">$ dc sample.dc amean.cd
Sum: 18
Mean: 3.6
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=={{header|Delphi}}==
<syntaxhighlight lang=
{$APPTYPE CONSOLE}
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=={{header|Dyalect}}==
<syntaxhighlight lang="dyalect">func avg(args...) {
var acc = .0
var len = 0
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Slightly generalized to support any object that allows iteration.
<syntaxhighlight lang="e">def meanOrZero(numbers) {
var count := 0
var sum := 0
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=={{header|EasyLang}}==
<syntaxhighlight lang="text">func mean . f[] r .
for i range len f[]
s += f[i]
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=={{header|EchoLisp}}==
'''(mean values)''' is included in math.lib. values may be a list, vector, sequence, or any kind of procrastinator.
<syntaxhighlight lang="scheme">
(lib 'math)
(mean '(1 2 3 4)) ;; mean of a list
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=={{header|ECL}}==
<syntaxhighlight lang="ecl">
AveVal(SET OF INTEGER s) := AVE(s);
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=={{header|Elena}}==
ELENA 5.0:
<syntaxhighlight lang="elena">import extensions;
extension op
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=={{header|Elixir}}==
<syntaxhighlight lang="elixir">defmodule Average do
def mean(list), do: Enum.sum(list) / length(list)
end</syntaxhighlight>
=={{header|Emacs Lisp}}==
<syntaxhighlight lang="lisp">(defun mean (lst)
(/ (float (apply '+ lst)) (length lst)))
(mean '(1 2 3 4))</syntaxhighlight>
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{{libheader|Calc}}
<syntaxhighlight lang="lisp">(let ((x '(1 2 3 4)))
(calc-eval "vmean($1)" nil (append '(vec) x)))</syntaxhighlight>
=={{header|Erlang}}==
<syntaxhighlight lang="erlang">mean([]) -> 0;
mean(L) -> lists:sum(L)/erlang:length(L).</syntaxhighlight>
=={{header|Euphoria}}==
<syntaxhighlight lang=
atom sum
if length(s) = 0 then
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Assuming the values are entered in the A column, type into any cell which will not be part of the list:
<syntaxhighlight lang="excel">=AVERAGE(A1:A10)</syntaxhighlight>
Assuming 10 values will be entered, alternatively, you can just type:
<syntaxhighlight lang="excel">=AVERAGE(</syntaxhighlight>
and then select the start and end cells, not necessarily in the same row or column.
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=={{header|F_Sharp|F#}}==
The following computes the running mean using a tail-recursive approach. If we just sum all the values then divide by the number of values then we will suffer from overflow problems for large lists. See [[wp:Moving_average|wikipedia]] about the moving average computation.
<syntaxhighlight lang="fsharp">let avg (a:float) (v:float) n =
a + (1. / ((float n) + 1.)) * (v - a)
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Checking this:
<syntaxhighlight lang="fsharp"> > mean_series [1; 8; 2; 8; 1; 7; 1; 8; 2; 7; 3; 6; 1; 8; 100] ;;
val it : float = 10.86666667
> mean_series [] ;;
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We can also make do with the built-in ''List.average'' function:
<syntaxhighlight lang="fsharp">List.average [4;1;7;5;8;4;5;2;1;5;2;5]</syntaxhighlight>
=={{header|Factor}}==
<syntaxhighlight lang="factor">USING: math math.statistics ;
: arithmetic-mean ( seq -- n )
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Tests:
<syntaxhighlight lang="factor">( scratchpad ) { 2 3 5 } arithmetic-mean >float
3.333333333333333</syntaxhighlight>
=={{header|Fantom}}==
<syntaxhighlight lang="fantom">
class Main
{
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=={{header|Fish}}==
<syntaxhighlight lang=
v< +<>0n; >n;
>l1)?^&,n;</syntaxhighlight>
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=={{header|Forth}}==
<syntaxhighlight lang="forth">: fmean ( addr n -- f )
0e
dup 0= if 2drop exit then
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=={{header|Fortran}}==
In ISO Fortran 90 or later, use the SUM intrinsic, the SIZE intrinsic and the MAX intrinsic (to avoid divide by zero):
<syntaxhighlight lang="fortran">real, target, dimension(100) :: a = (/ (i, i=1, 100) /)
real, dimension(5,20) :: b = reshape( a, (/ 5,20 /) )
real, pointer, dimension(:) :: p => a(2:1) ! pointer to zero-length array
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=={{header|FreeBASIC}}==
<syntaxhighlight lang="freebasic">
' FB 1.05.0 Win64
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=={{header|Frink}}==
The following works on arrays or sets. If the collection is empty, this returns the special value <CODE>undef</CODE>.
<syntaxhighlight lang="frink">
mean[x] := length[x] > 0 ? sum[x] / length[x] : undef
</syntaxhighlight>
=={{header|GAP}}==
<syntaxhighlight lang="gap">Mean := function(v)
local n;
n := Length(v);
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=={{header|GEORGE}}==
<syntaxhighlight lang=
0
1, n rep (i)
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This works for arrays of integers.
<syntaxhighlight lang="text">
DIM a%(10)
FOR i%=0 TO 10
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A little more elaborate that the task requires. The function "mean" fulfills the task of "a program to find the mean." As a Go idiom, it returns an ok value of true if result m is valid. An ok value of false means the input "vector" (a Go slice) was empty. The fancy accuracy preserving algorithm is a little more than was called more. The program main is a test program demonstrating the ok idiom and several data cases.
<syntaxhighlight lang="go">package main
import (
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=={{header|Groovy}}==
<syntaxhighlight lang="groovy">def avg = { list -> list == [] ? 0 : list.sum() / list.size() }</syntaxhighlight>
Test Program:
<syntaxhighlight lang="groovy">println avg(0..9)
println avg([2,2,2,4,2])
println avg ([])</syntaxhighlight>
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=={{header|Haskell}}==
This function works if the element type is an instance of Fractional:
<syntaxhighlight lang="haskell">mean :: (Fractional a) => [a] -> a
mean [] = 0
mean xs = sum xs / Data.List.genericLength xs</syntaxhighlight>
But some types, e.g. integers, are not Fractional; the following function works for all Real types:
<syntaxhighlight lang="haskell">meanReals :: (Real a, Fractional b) => [a] -> b
meanReals = mean . map realToFrac</syntaxhighlight>
If you want to avoid keeping the list in memory and traversing it twice:
<syntaxhighlight lang="haskell">{-# LANGUAGE BangPatterns #-}
import Data.List (foldl') --'
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=={{header|HicEst}}==
<syntaxhighlight lang="hicest">REAL :: vec(100) ! no zero-length arrays in HicEst
vec = $ - 1/2 ! 0.5 ... 99.5
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=={{header|Hy}}==
Returns <tt>None</tt> if the input is of length zero.
<syntaxhighlight lang="clojure">(defn arithmetic-mean [xs]
(if xs
(/ (sum xs) (len xs))))</syntaxhighlight>
=={{header|Icon}} and {{header|Unicon}}==
<syntaxhighlight lang="icon">procedure main(args)
every (s := 0) +:= !args
write((real(s)/(0 ~= *args)) | 0)
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If truly only the mean is wanted, one could use
<syntaxhighlight lang="idl">x = [3,1,4,1,5,9]
print,mean(x)</syntaxhighlight>
But <tt>mean()</tt> is just a thin wrapper returning the zeroth element of <tt>moment()</tt> :
<syntaxhighlight lang="idl">print,moment(x)
; ==>
3.83333 8.96667 0.580037 -1.25081</syntaxhighlight>
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=={{header|J}}==
<syntaxhighlight lang="j">mean=: +/ % #</syntaxhighlight>
That is, sum divided by the number of items. The verb also works on higher-ranked arrays. For example:
<syntaxhighlight lang="j"> mean 3 1 4 1 5 9
3.83333
mean $0 NB. $0 is a zero-length vector
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The computation can also be written as a loop. It is shown here for comparison only and is highly non-preferred compared to the version above.
<syntaxhighlight lang="j">mean1=: 3 : 0
z=. 0
for_i. i.#y do. z=. z+i{y end.
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{{works with|Java|1.5+}}
<syntaxhighlight lang="java5">public static double avg(double... arr) {
double sum = 0.0;
for (double x : arr) {
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===ES5===
<syntaxhighlight lang="javascript">function mean(array)
{
var sum = 0, i;
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Using the native function `.forEach()`:
<syntaxhighlight lang="javascript">function mean(array) {
var sum = 0;
array.forEach(function(value){
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Using the native function `.reduce()`:
<syntaxhighlight lang="javascript">function mean(array) {
return !array.length ? 0
: array.reduce(function(pre, cur, i) {
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Extending the `Array` prototype:
<syntaxhighlight lang="javascript">Array.prototype.mean = function() {
return !this.length ? 0
: this.reduce(function(pre, cur, i) {
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{{libheader|Functional}}
<syntaxhighlight lang="javascript">function mean(a)
{
return a.length ? Functional.reduce('+', 0, a) / a.length : 0;
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===ES6===
<syntaxhighlight lang=
// mean :: [Num] => (Num | NaN)
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{{Out}}
<syntaxhighlight lang=
=={{header|jq}}==
The mean of an array of numbers can be computed by simply writing
<syntaxhighlight lang="jq">add/length</syntaxhighlight>
This definition raises an error condition if the array is empty, so it may make sense to define '''mean''' as follows, '''null''' being jq's null value:
<syntaxhighlight lang="jq">def mean: if length == 0 then null
else add/length
end;</syntaxhighlight>
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=={{header|Julia}}==
Julia's built-in mean function accepts AbstractArrays (vector, matrix, etc.)
<syntaxhighlight lang="julia">julia> using Statistics; mean([1,2,3])
2.0
julia> mean(1:10)
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=={{header|K}}==
<syntaxhighlight lang="k"> mean: {(+/x)%#x}
mean 1 2 3 5 7
3.6
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Kotlin has builtin functions for some collection types.
Example:
<syntaxhighlight lang="scala">fun main(args: Array<String>) {
val nums = doubleArrayOf(1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0)
println("average = %f".format(nums.average()))
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=={{header|KQL}}==
<syntaxhighlight lang="kql">
let dataset = datatable(values:real)[
1, 1.5, 3, 5, 6.5];
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=={{header|Lambdatalk}}==
<syntaxhighlight lang="scheme">
{def mean
{lambda {:s}
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{{works with|langur|0.6.6}}
<syntaxhighlight lang="langur">val .mean = f(.x) fold(f{+}, .x) / len(.x)
writeln " custom: ", .mean([7, 3, 12])
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=={{header|Lasso}}==
<syntaxhighlight lang=
not #a->size ? return 0
local(x = 0.0)
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=== 1-Arity ===
<syntaxhighlight lang="lisp">
(defun mean (data)
(/ (lists:sum data)
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Usage:
<syntaxhighlight lang="lisp">> (mean '(1 1))
1.0
> (mean '(1 2))
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Functions in LFE (and Erlang) have set arity, but macros can be used to provide the same use as n-arity functions:
<syntaxhighlight lang="lisp">(defmacro mean args
`(/ (lists:sum ,args)
,(length args)))</syntaxhighlight>
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Usage:
<syntaxhighlight lang="lisp">> (mean 42)
42.0
> (mean 18 66)
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=={{header|Liberty BASIC}}==
<syntaxhighlight lang="lb">total=17
dim nums(total)
for i = 1 to total
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=={{header|Limbo}}==
<syntaxhighlight lang=
include "sys.m";
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=={{header|Lingo}}==
<syntaxhighlight lang=
on mean (v)
case ilk(v) of
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end</syntaxhighlight>
<syntaxhighlight lang=
-- 1.7500
put mean(vector(1.2, 4.7, 5.6))
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=={{header|LiveCode}}==
Livecode provides arithmeticMean (avg, average) built-in.
<syntaxhighlight lang=
average(empty) -- 0</syntaxhighlight>
=={{header|Logo}}==
<syntaxhighlight lang="logo">to average :l
if empty? :l [output 0]
output quotient apply "sum :l count :l
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=={{header|Logtalk}}==
Logtalk's standard library provides an arithmetic average predicate but we ignore it here. Representing a vector using a list:
<syntaxhighlight lang="logtalk">
:- object(averages).
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</syntaxhighlight>
Sample output:
<syntaxhighlight lang="text">
| ?- averages::arithmetic([1,2,3,4,5,6,7,8,9,10], Mean).
Mean = 5.5
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=={{header|LSL}}==
<syntaxhighlight lang=
integer MAX_VALUE = 100;
default {
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=={{header|Lua}}==
<syntaxhighlight lang="lua">function mean (numlist)
if type(numlist) ~= 'table' then return numlist end
num = 0
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=={{header|Lucid}}==
<syntaxhighlight lang="lucid">avg(x)
where
sum = first(x) fby sum + next(x);
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directly, but it is a little bit clearer to keep them separated.
<syntaxhighlight lang="m4">define(`extractdec', `ifelse(eval(`$1%100 < 10'),1,`0',`')eval($1%100)')dnl
define(`fmean', `eval(`($2/$1)/100').extractdec(eval(`$2/$1'))')dnl
define(`mean', `rmean(`$#', $@)')dnl
define(`rmean', `ifelse(`$3', `', `fmean($1,$2)',dnl
`rmean($1, eval($2+$3), shift(shift(shift($@))))')')dnl</syntaxhighlight>
<syntaxhighlight lang="m4">mean(0,100,200,300,400,500,600,700,800,900,1000)</syntaxhighlight>
=={{header|Maple}}==
This version accepts any indexable structure, including numeric arrays. We use a call to the "environment variable" (dynamically scoped global) "Normalizer" to provide normalization of symbolic expressions. This can be set by the caller to adjust the strength of normalization desired.
<syntaxhighlight lang=
mean := proc( a :: indexable )
local i;
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</syntaxhighlight>
For example:
<syntaxhighlight lang=
> mean( { 1/2, 2/3, 3/4, 4/5, 5/6 } ); # set
71
Line 2,020:
</syntaxhighlight>
A slightly different design computes the mean of all its arguments, instead of requiring a single container argument. This seems a little more Maple-like for a general purpose utility.
<syntaxhighlight lang=
This can be called as in the following examples.
<syntaxhighlight lang=
> mean( 1, 2, 3, 4, 5 );
3
Line 2,035:
</syntaxhighlight>
If desired, we can add argument type-checking as follows.
<syntaxhighlight lang=
=={{header|Mathematica}} / {{header|Wolfram Language}}==
Modify the built-in Mean function to give 0 for empty vectors (lists in Mathematica):
<syntaxhighlight lang="mathematica">Unprotect[Mean];
Mean[{}] := 0</syntaxhighlight>
Examples:
<syntaxhighlight lang="mathematica">Mean[{3,4,5}]
Mean[{3.2,4.5,5.9}]
Mean[{-4, 1.233}]
Line 2,049:
Mean[{a,c,Pi,-3,a}]</syntaxhighlight>
gives (a set of integers gives back an integer or a rational, a set of floats gives back a float, a set of rationals gives a rational back, a list of symbols and numbers keeps the symbols exact and a mix of exact and approximate numbers gives back an approximate number):
<syntaxhighlight lang="mathematica">4
4.53333
-1.3835
Line 2,066:
To make it more interesting I find the Arithmectic Mean of more than a million Integers.
<syntaxhighlight lang="text">
/*Arithmetic Mean of a large number of Integers
- or - solve a very large constraint matrix
Line 2,095:
When run this produces:
<syntaxhighlight lang="text">
GLPSOL: GLPK LP/MIP Solver, v4.47
Parameter(s) specified in the command line:
Line 2,121:
=={{header|MATLAB}}==
<syntaxhighlight lang=
meanValue = mean(setOfValues);
end</syntaxhighlight>
=={{header|Maxima}}==
<syntaxhighlight lang="maxima">load("descriptive");
mean([2, 7, 11, 17]);</syntaxhighlight>
=={{header|MAXScript}}==
<syntaxhighlight lang="maxscript">fn mean data =
(
total = 0
Line 2,143:
=={{header|Mercury}}==
<syntaxhighlight lang="mercury">:- module arithmetic_mean.
:- interface.
Line 2,167:
mean function is called with an empty list.
<syntaxhighlight lang="mercury">:- func mean(list(float)::in(non_empty_list)) = (float::out).
mean(Ns) = foldl((+), Ns, 0.0) / float(length(Ns)).</syntaxhighlight>
Line 2,174:
Returns <code>nan</code> for an empty quotation.
{{works with|min|0.19.3}}
<syntaxhighlight lang="min">(((0 (+) reduce) (size /)) cleave) :mean
(2 3 5) mean print</syntaxhighlight>
{{out}}
Line 2,183:
=={{header|MiniScript}}==
<syntaxhighlight lang=
avg = function(arr)
Line 2,196:
=={{header|МК-61/52}}==
<syntaxhighlight lang="text">0 П0 П1 С/П ИП0 ИП1 * + ИП1 1
+ П1 / П0 БП 03</syntaxhighlight>
Line 2,204:
=={{header|Modula-2}}==
<syntaxhighlight lang="modula2">PROCEDURE Avg;
VAR avg : REAL;
Line 2,215:
END Avg;</syntaxhighlight>
OR
<syntaxhighlight lang="modula2">PROCEDURE Average (Data : ARRAY OF REAL; Samples : CARDINAL) : REAL;
(* Calculate the average over 'Samples' values, stored in array 'Data'. *)
Line 2,231:
=={{header|MUMPS}}==
<syntaxhighlight lang=
;X is assumed to be a list of numbers separated by "^"
QUIT:'$DATA(X) "No data"
Line 2,250:
=={{header|Nanoquery}}==
<syntaxhighlight lang=
sum = 0
for n in lst
Line 2,263:
=={{header|Nemerle}}==
<syntaxhighlight lang=
using System.Console;
using Nemerle.Collections;
Line 2,282:
=={{header|NetRexx}}==
<syntaxhighlight lang=
options replace format comments java crossref symbols nobinary
Line 2,357:
=={{header|NewLISP}}==
<syntaxhighlight lang=
(if (empty? Lst)
0
Line 2,367:
=={{header|Nial}}==
in the standard way, mean is
<syntaxhighlight lang="nial">mean is / [sum, tally]
mean 6 2 4
Line 2,373:
but it fails with 0 length vectors. so using a tally with a minimum value 1
<syntaxhighlight lang="nial">dtally is recur [ empty rest, 1 first, 1 first, plus, rest ]
mean is / [sum, dtally]
Line 2,381:
=={{header|Nim}}==
{{trans|C}}
<syntaxhighlight lang="nim">import strutils
proc mean(xs: openArray[float]): float =
Line 2,401:
=={{header|Niue}}==
<syntaxhighlight lang=
[ [ , len 1 - at ! ] len 3 - times swap , ] 'map ; ( a Lisp like map, to sum the stack )
[ len 'n ; [ + ] 0 n swap-at map n / ] 'avg ;
Line 2,413:
=={{header|Oberon-2}}==
Oxford Oberon-2
<syntaxhighlight lang="oberon2">
MODULE AvgMean;
IMPORT Out;
Line 2,450:
=={{header|Objeck}}==
<syntaxhighlight lang="objeck">
function : native : PrintAverage(values : FloatVector) ~ Nil {
values->Average()->PrintLine();
Line 2,459:
These functions return a float:
<syntaxhighlight lang="ocaml">let mean_floats = function
| [] -> 0.
| xs -> List.fold_left (+.) 0. xs /. float_of_int (List.length xs)
Line 2,475:
would rather be handled by an exception.
<syntaxhighlight lang="ocaml">let mean_floats xs =
if xs = [] then
invalid_arg "empty list"
Line 2,504:
GNU Octave has a <tt>mean</tt> function (from statistics package), but it does not handle an empty vector; an implementation that allows that is:
<syntaxhighlight lang="octave">function m = omean(l)
if ( numel(l) == 0 )
m = 0;
Line 2,517:
If the data contains missing value, encoded as non-a-number:
<syntaxhighlight lang="octave">function m = omean(l)
n = sum(~isnan(l));
l(isnan(l))=0;
Line 2,526:
=={{header|Oforth}}==
<syntaxhighlight lang=
x sum
x size dup ifZero: [ 2drop null ] else: [ >float / ]
Line 2,540:
=={{header|ooRexx}}==
<syntaxhighlight lang=
call testAverage .array~of(10, 9, 8, 7, 6, 5, 4, 3, 2, 1)
call testAverage .array~of(10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 0, 0, 0, .11)
Line 2,580:
=={{header|Oz}}==
A version working on floats:
<syntaxhighlight lang="oz">declare
fun {Mean Xs}
{FoldL Xs Number.'+' 0.0} / {Int.toFloat {Length Xs}}
Line 2,588:
=={{header|PARI/GP}}==
<syntaxhighlight lang="parigp">avg(v)={
if(#v,vecsum(v)/#v)
};</syntaxhighlight>
=={{header|Pascal}}==
<syntaxhighlight lang="pascal">Program Mean;
function DoMean(vector: array of double): double;
Line 2,633:
Alternative version using the Math unit:
<syntaxhighlight lang="pascal">Program DoMean;
uses math;
const
Line 2,653:
=={{header|Perl}}==
<syntaxhighlight lang="perl">sub avg {
@_ or return 0;
my $sum = 0;
Line 2,663:
=={{header|Phix}}==
<!--<syntaxhighlight lang=
<span style="color: #008080;">with</span> <span style="color: #008080;">javascript_semantics</span>
<span style="color: #008080;">function</span> <span style="color: #000000;">mean</span><span style="color: #0000FF;">(</span><span style="color: #004080;">sequence</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">)</span>
Line 2,674:
=={{header|Phixmonti}}==
<syntaxhighlight lang=
len swap sum swap / print</syntaxhighlight>
=={{header|PHP}}==
<syntaxhighlight lang="php">$nums = array(3, 1, 4, 1, 5, 9);
if ($nums)
echo array_sum($nums) / count($nums), "\n";
Line 2,685:
=={{header|PicoLisp}}==
<syntaxhighlight lang=
(if (atom Lst)
0
Line 2,694:
=={{header|PL/I}}==
<syntaxhighlight lang="pli">arithmetic_mean = sum(A)/dimension(A,1);</syntaxhighlight>
=={{header|Plain English}}==
<syntaxhighlight lang="plainenglish">To run:
Start up.
Demonstrate finding the arithmetic mean.
Line 2,755:
=={{header|Pop11}}==
<syntaxhighlight lang="pop11">define mean(v);
lvars n = length(v), i, s = 0;
if n = 0 then
Line 2,768:
=={{header|PostScript}}==
<syntaxhighlight lang="text">
/findmean{
/x exch def
Line 2,788:
{{libheader|initlib}}
{{works with|Ghostscript}}
<syntaxhighlight lang="postscript">
/avg {
dup length
Line 2,801:
=={{header|PowerShell}}==
The hard way by calculating a sum and dividing:
<syntaxhighlight lang="powershell">function mean ($x) {
if ($x.Count -eq 0) {
return 0
Line 2,813:
}</syntaxhighlight>
or, shorter, by using the <code>Measure-Object</code> cmdlet which already knows how to compute an average:
<syntaxhighlight lang="powershell">function mean ($x) {
if ($x.Count -eq 0) {
return 0
Line 2,822:
=={{header|Processing}}==
<syntaxhighlight lang="processing">float mean(float[] arr) {
float out = 0;
for (float n : arr) {
Line 2,834:
{{works with|SWI-Prolog|6.6}}
<syntaxhighlight lang="prolog">
mean(List, Mean) :-
length(List, Length),
Line 2,842:
=={{header|PureBasic}}==
<syntaxhighlight lang=
Protected sum=0
Line 2,855:
{{works with|Python|3.0}}.<br>{{works with|Python|2.6}}<br>
Uses [http://docs.python.org/3.3/library/math.html?highlight=fsum#math.fsum fsum] which tracks multiple partial sums to avoid losing precision
<syntaxhighlight lang="python">from math import fsum
def average(x):
return fsum(x)/float(len(x)) if x else 0
Line 2,862:
{{out}}
<syntaxhighlight lang="python">2.3
2.3</syntaxhighlight>
{{works with|Python|2.5}}
<syntaxhighlight lang="python">def average(x):
return sum(x)/float(len(x)) if x else 0
print (average([0,0,3,1,4,1,5,9,0,0]))
Line 2,874:
{{out}}
(Notice how the second call gave the wrong result)
<syntaxhighlight lang="python">2.3
1e-21</syntaxhighlight>
{{works with|Python|2.4}}
<syntaxhighlight lang="python">def avg(data):
if len(data)==0:
return 0
Line 2,887:
{{out}}
<syntaxhighlight lang="python">2.3</syntaxhighlight>
{{works with|Python|3.4}}
Since 3.4, Python has a [[http://docs.python.org/3/library/statistics.html statistics] library in the stdlib, which takes care of these precision overflow issues in a way that works for all standard types, not just float, even with values way too big or small to fit in a float. (For Python 2.6-2.7, there's a backport available on PyPI.)
<syntaxhighlight lang="python">>>> from statistics import mean
>>> mean([1e20,-1e-20,3,1,4,1,5,9,-1e20,1e-20])
2.3
Line 2,904:
=={{header|Q}}==
A built-in solution is <tt>avg</tt>. An implementation of it could be:
<syntaxhighlight lang="q">mean:{(sum x)%count x}</syntaxhighlight>
=={{header|Quackery}}==
Line 2,910:
Using the Quackery big number rational arithmetic library <code>bigrat.qky</code>.
<syntaxhighlight lang=
[ [] swap times
Line 2,990:
R has its <tt>mean</tt> function but it does not allow for NULL (void vectors or whatever) as argument: in this case it raises a warning and the result is NA. An implementation that does not suppress the warning could be:
<syntaxhighlight lang="rsplus">omean <- function(v) {
m <- mean(v)
ifelse(is.na(m), 0, m)
Line 2,999:
Racket's math library (available in v5.3.2 and newer) comes with a <tt>mean</tt> function that works on arbitrary sequences.
<syntaxhighlight lang="racket">
#lang racket
(require math)
Line 3,012:
{{works with|Rakudo|2015.10-11}}
<syntaxhighlight lang=
multi mean (@a) { ([+] @a) / @a }</syntaxhighlight>
=={{header|Rapira}}==
<syntaxhighlight lang=
sum := 0
for N from 1 to #arr do
Line 3,025:
=={{header|REBOL}}==
<syntaxhighlight lang=
Title: "Arithmetic Mean (Average)"
URL: http://rosettacode.org/wiki/Average/Arithmetic_mean
Line 3,054:
=={{header|Red}}==
Red comes with the <code>average</code> function.
<syntaxhighlight lang="red">Red ["Arithmetic mean"]
print average []
Line 3,065:
The source code for <code>average</code>:
<syntaxhighlight lang="red">average: func [
"Returns the average of all values in a block"
block [block! vector! paren! hash!]
Line 3,075:
=={{header|ReScript}}==
<syntaxhighlight lang=
let num = Js.Array.length(arr)
Line 3,093:
A check is made to validate if the numbers in the list are all numeric.
<syntaxhighlight lang="rexx">/*REXX program finds the averages/arithmetic mean of several lists (vectors) or CL input*/
parse arg @.1; if @.1='' then do; #=6 /*vector from the C.L.?*/
@.1 = 10 9 8 7 6 5 4 3 2 1
Line 3,154:
=={{header|Ring}}==
<syntaxhighlight lang="ring">
nums = [1,2,3,4,5,6,7,8,9,10]
sum = 0
Line 3,170:
This is a simple rewrite of the dc version above. This works on an HP 48. "->" is a single right arrow character on the 48. Feel free to alter this code as necessary to work on RPL/2.
<syntaxhighlight lang="rpl/2">1 2 3 5 7
AMEAN
<< DEPTH DUP 'N' STO ->LIST ΣLIST N / >>
Line 3,176:
=={{header|Ruby}}==
<syntaxhighlight lang="ruby">def mean(nums)
nums.sum(0.0) / nums.size
end
Line 3,197:
=={{header|Run BASIC}}==
<syntaxhighlight lang="runbasic">print "Gimme the number in the array:";input numArray
dim value(numArray)
for i = 1 to numArray
Line 3,210:
=={{header|Rust}}==
<syntaxhighlight lang="rust">fn sum(arr: &[f64]) -> f64 {
arr.iter().fold(0.0, |p,&q| p + q)
}
Line 3,231:
=={{header|Sather}}==
Built to work with VEC, ("geometric" vectors), whose elements must be floats. A 0-dimension vector yields "nan".
<syntaxhighlight lang="sather">class VECOPS is
mean(v:VEC):FLT is
m ::= 0.0;
Line 3,249:
Using Scala 2.7, this has to be defined for each numeric type:
<syntaxhighlight lang="scala">def mean(s: Seq[Int]) = s.foldLeft(0)(_+_) / s.size</syntaxhighlight>
However, Scala 2.8 gives much more flexibility, but you still have to opt
between integral types and fractional types. For example:
<syntaxhighlight lang="scala">def mean[T](s: Seq[T])(implicit n: Integral[T]) = {
import n._
s.foldLeft(zero)(_+_) / fromInt(s.size)
Line 3,267:
Alas, Scala 2.8 also simplifies the task in another way:
<syntaxhighlight lang="scala">def mean[T](s: Seq[T])(implicit n: Fractional[T]) = n.div(s.sum, n.fromInt(s.size))</syntaxhighlight>
Here we show a function that supports fractional types. Instead of importing the definitions
Line 3,275:
=={{header|Scheme}}==
<syntaxhighlight lang="scheme">(define (mean l)
(if (null? l)
0
Line 3,284:
=={{header|Seed7}}==
<syntaxhighlight lang="seed7">$ include "seed7_05.s7i";
include "float.s7i";
Line 3,311:
=={{header|SenseTalk}}==
SenseTalk has a built-in average function.
<syntaxhighlight lang="sensetalk">put the average of [12,92,-17,66,128]
put average(empty)
Line 3,322:
=={{header|Sidef}}==
<syntaxhighlight lang="ruby">func avg(Array list) {
list.len > 0 || return 0;
list.sum / list.len;
Line 3,341:
=={{header|Slate}}==
<syntaxhighlight lang="slate">[|:list| (list reduce: #+ `er ifEmpty: [0]) / (list isEmpty ifTrue: [1] ifFalse: [list size])] applyWith: #(3 1 4 1 5 9).
[|:list| (list reduce: #+ `er ifEmpty: [0]) / (list isEmpty ifTrue: [1] ifFalse: [list size])] applyWith: {}.</syntaxhighlight>
=={{header|Smalltalk}}==
<syntaxhighlight lang="smalltalk">
| numbers |
Line 3,356:
</syntaxhighlight>
However, the empty check can be omitted, as inject returns the injected value for empty collections, and we probably do not care for the average of nothing (i.e. the division by zero exception):
<syntaxhighlight lang="smalltalk">
| numbers |
Line 3,365:
{{works with|Pharo}}
{{works with|Smalltalk/X}}
<syntaxhighlight lang="smalltalk">
| numbers |
Line 3,372:
</syntaxhighlight>
or
<syntaxhighlight lang="smalltalk">
| numbers |
Line 3,385:
{{works with|CSnobol}}
<syntaxhighlight lang=
avg i = i + 1; sum = sum + a<i> :s(avg)
avg = 1.0 * sum / prototype(a) :(return)
Line 3,406:
=={{header|SQL}}==
Tested on Oracle 11gR2, the more limited the tool, the more resourceful one becomes :)
<syntaxhighlight lang=
create table "numbers" ("datapoint" integer);
Line 3,414:
</syntaxhighlight>
...or...
<syntaxhighlight lang=
=={{header|Standard ML}}==
These functions return a real:
<syntaxhighlight lang="sml">fun mean_reals [] = 0.0
| mean_reals xs = foldl op+ 0.0 xs / real (length xs);
Line 3,432:
would rather be handled by an exception.
<syntaxhighlight lang="sml">fun mean_reals [] = raise Empty
| mean_reals xs = let
val (total, length) =
Line 3,456:
=== Mean of a dataset variable ===
Illustration of the mean on the population (in millions) in january 2016 of a few european countries (source [http://appsso.eurostat.ec.europa.eu/nui/show.do?dataset=demo_gind&lang=fr Eurostat]).
<syntaxhighlight lang="text">clear all
input str20 country population
Belgium 11311.1
Line 3,489:
=== Mean in Mata ===
<syntaxhighlight lang="stata">mata
a=11311.1\7153.8\10553.8\5707.3\
82175.7\1315.9\4724.7\10783.7
Line 3,497:
=={{header|Swift}}==
<syntaxhighlight lang="swift">func meanDoubles(s: [Double]) -> Double {
return s.reduce(0, +) / Double(s.count)
}
Line 3,505:
=={{header|Tcl}}==
<syntaxhighlight lang="tcl">package require Tcl 8.5
proc mean args {
if {[set num [llength $args]] == 0} {return 0}
Line 3,513:
=={{header|TI-83 BASIC}}==
<syntaxhighlight lang="ti83b">Mean(Ans</syntaxhighlight>
=={{header|TI-89 BASIC}}==
<syntaxhighlight lang="ti89b">Define rcmean(nums) = when(dim(nums) = 0, 0, mean(nums))</syntaxhighlight>
=={{header|Trith}}==
<syntaxhighlight lang="trith">: mean dup empty? [drop 0] [dup [+] foldl1 swap length /] branch ;
[3 1 4 1 5 9] mean</syntaxhighlight>
=={{header|TypeScript}}==
<syntaxhighlight lang="typescript">
function mean(numbersArr)
{
Line 3,545:
=={{header|UNIX Shell}}==
1) First solution with bash (V >= 3), works with floats :
<syntaxhighlight lang="bash1">echo "`cat f | paste -sd+ | bc -l` / `cat f | wc -l`" | bc -l
</syntaxhighlight>
<syntaxhighlight lang="bash1">cat f
1
2
Line 3,573:
2) This example uses <tt>expr</tt>, so it only works with integers. It checks that each string in the list is an integer.
<syntaxhighlight lang="bash">mean() {
if expr $# >/dev/null; then
(count=0
Line 3,603:
Uses [[ksh93]]-style process substitution. Also overwrites the file named <tt>count</tt> in the current directory.
{{works with|bash}}
<syntaxhighlight lang="bash">term() {
b=$1;res=$2
echo "scale=5;$res+$b" | bc
Line 3,627:
=={{header|Ursa}}==
<syntaxhighlight lang="ursa">#
# arithmetic mean
#
Line 3,642:
There is a library function for means already, although it doesn't cope with
empty vectors. A mean function could be defined as shown for this task.
<syntaxhighlight lang=
#import flo
Line 3,654:
=={{header|V}}==
<syntaxhighlight lang="v">[mean
[sum 0 [+] fold].
dup sum
Line 3,662:
=={{header|Vala}}==
Using array to hold the numbers of the list:
<syntaxhighlight lang="vala">
double arithmetic(double[] list){
double mean;
Line 3,697:
=={{header|VBA}}==
<syntaxhighlight lang="vb">Private Function mean(v() As Double, ByVal leng As Integer) As Variant
Dim sum As Double, i As Integer
sum = 0: i = 0
Line 3,733:
=={{header|VBScript}}==
<syntaxhighlight lang="vb">
Function mean(arr)
size = UBound(arr) + 1
Line 3,752:
=={{header|Vedit macro language}}==
The numeric data is stored in current edit buffer as ASCII strings, one value per line.
<syntaxhighlight lang="vedit">#1 = 0 // Sum
#2 = 0 // Count
BOF
Line 3,765:
=={{header|Vim Script}}==
Throws an exception if the list is empty.
<syntaxhighlight lang="vim">function Mean(lst)
if empty(a:lst)
throw "Empty"
Line 3,777:
=={{header|Vlang}}==
<syntaxhighlight lang="vlang">import math
import arrays
Line 3,819:
=={{header|Wart}}==
<syntaxhighlight lang="python">def (mean l)
sum.l / len.l</syntaxhighlight>
Line 3,827:
=={{header|WDTE}}==
<syntaxhighlight lang=
let a => import 'arrays';
Line 3,838:
Usage:
<syntaxhighlight lang=
Output:
Line 3,844:
=={{header|Wortel}}==
<syntaxhighlight lang="wortel">@let {
; using a fork (sum divided-by length)
mean1 @(@sum / #)
Line 3,860:
=={{header|Wren}}==
<syntaxhighlight lang="ecmascript">class Arithmetic {
static mean(arr) {
if (arr.count == 0) Fiber.abort("Length must be greater than zero")
Line 3,870:
=={{header|XLISP}}==
The specification calls for a function that takes a vector; for convenience, we convert this vector internally to a list. The mean of a zero-length vector is returned as <tt>nil</tt>, equivalent to the empty list or logical <tt>false</tt>.
<syntaxhighlight lang="lisp">(defun mean (v)
(if (= (vector-length v) 0)
nil
Line 3,877:
=={{header|XPL0}}==
<syntaxhighlight lang=
code real RlOut=48;
Line 3,904:
Where <code>$values</code> is some variable indicating a set of nodes containing numbers, the average is given by the XPath expression:
<syntaxhighlight lang="xpath">sum($values) div count($values)</syntaxhighlight>
===Runnable example===
<syntaxhighlight lang="xml"><xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:output method="text"/>
Line 3,919:
Sample input:
<syntaxhighlight lang="xml"><numbers>
<!-- Average is 2.4 -->
<number>1</number>
Line 3,929:
=={{header|Yorick}}==
<syntaxhighlight lang="yorick">func mean(x) {
if(is_void(x)) return 0;
return x(*)(avg);
Line 3,936:
=={{header|zkl}}==
Converts int to floats (implicitly):
<syntaxhighlight lang="zkl">fcn mean(a,b,c,etc){ z:=vm.arglist; z.reduce('+,0.0)/z.len() }
mean(3,1,4,1,5,9); //-->3.83333
mean(); //-->Exception thrown: MathError(NaN (Not a number))</syntaxhighlight>
To pass in a vector/list:
<syntaxhighlight lang="zkl">fcn meanV(z){ z.reduce('+,0.0)/z.len() }
meanV(T(3,1,4,1,5,9)); // --> 3.83333</syntaxhighlight>
=={{header|Zoea}}==
<syntaxhighlight lang=
program: average
case: 1
Line 3,955:
=={{header|zonnon}}==
<syntaxhighlight lang="zonnon">
module Averages;
type
| |||