Hash from two arrays: Difference between revisions
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:-make_hash_pure([un,deux,trois],[[a,b,c],[d,e,f],[g,h,i]],L),findall(M,(member(M,L),assert(M)),L).</lang> |
:-make_hash_pure([un,deux,trois],[[a,b,c],[d,e,f],[g,h,i]],L),findall(M,(member(M,L),assert(M)),L).</lang> |
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=={{header|PureBasic}}== |
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<lang PureBasic>Dim keys.s(3) |
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Dim vals.s(3) |
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NewMap Hash.s() |
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keys(0)="a" : keys(1)="b" : keys(2)="c" : keys(3)="d" |
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vals(0)="1" : vals(1)="2" : vals(2)="3" : vals(3)="4" |
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For n = 0 To 3 |
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Hash(keys(n))= vals(n) |
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Next |
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ForEach Hash() |
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Debug Hash() |
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Next</lang> |
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=={{header|Python}}== |
=={{header|Python}}== |
Revision as of 18:56, 14 March 2010
![Task](http://static.miraheze.org/rosettacodewiki/thumb/b/ba/Rcode-button-task-crushed.png/64px-Rcode-button-task-crushed.png)
You are encouraged to solve this task according to the task description, using any language you may know.
Using two Arrays of equal length, create a Hash object where the elements from one array (the keys) are linked to the elements of the other (the values)
ActionScript
<lang actionscript>package {
public class MyClass { public static function main():Void { var hash:Object = new Object(); var keys:Array = new Array("a", "b", "c"); var values:Array = new Array(1, 2, 3); for (var i:int = 0; i < keys.length(); i++) hash[keys[i]] = values[i]; } }
}</lang>
Ada
<lang ada>with Ada.Strings.Hash; with Ada.Containers.Hashed_Maps; with Ada.Text_Io; with Ada.Strings.Unbounded; use Ada.Strings.Unbounded;
procedure Hash_Map_Test is
function Equivalent_Key (Left, Right : Unbounded_String) return Boolean is begin return Left = Right; end Equivalent_Key; function Hash_Func(Key : Unbounded_String) return Ada.Containers.Hash_Type is begin return Ada.Strings.Hash(To_String(Key)); end Hash_Func; package My_Hash is new Ada.Containers.Hashed_Maps(Key_Type => Unbounded_String, Element_Type => Unbounded_String, Hash => Hash_Func, Equivalent_Keys => Equivalent_Key); type String_Array is array(Positive range <>) of Unbounded_String; Hash : My_Hash.Map; Key_List : String_Array := (To_Unbounded_String("foo"), To_Unbounded_String("bar"), To_Unbounded_String("val")); Element_List : String_Array := (To_Unbounded_String("little"), To_Unbounded_String("miss"), To_Unbounded_String("muffet"));
begin
for I in Key_List'range loop Hash.Insert(Key => (Key_List(I)), New_Item => (Element_List(I))); end loop; for I in Key_List'range loop Ada.Text_Io.Put_Line(To_String(Key_List(I)) & " => " & To_String(Hash.Element(Key_List(I)))); end loop;
end Hash_Map_Test;</lang>
Argile
<lang Argile>use std, array, hash
let keys = @["hexadecimal" "decimal" "octal" "binary"] let values = @[0xa 11 014 0b1101] (: 10 11 12 13 :) let hash = new hash of int for each val int i from 0 to 3
hash[keys[i]] = values[i]
del hash hash</lang>
AWK
Awk arrays are used for both lists and hash maps. <lang awk>$ awk 'BEGIN{split("one two three",a);
split("1 2 3",b); for(i=1;i in a;i++){c[a[i]]=b[i]}; for(i in c)print i,c[i] }'
three 3 two 2 one 1</lang>
C
There likely exist libraries that can be for creating hashes that are better than the following implementation. There are also better functions for obtaining hash values from strings. The following implementation tries to be somewhat generic to facilitate using alternative key and value types. <lang c>#include <stdio.h>
- include <stdlib.h>
- include <string.h>
- define KeyType const char *
- define ValType int
- define HASH_SIZE 4096
// hash function useful when KeyType is char * (string) unsigned strhashkey( const char * key, int max) {
unsigned h=0; unsigned hl, hr;
while(*key) { h += *key; hl= 0x5C5 ^ (h&0xfff00000 )>>18; hr =(h&0x000fffff ); h = hl ^ hr ^ *key++; } return h % max;
}
typedef struct sHme {
KeyType key; ValType value; struct sHme *link;
} *MapEntry;
typedef struct he {
MapEntry first, last;
} HashElement;
HashElement hash[HASH_SIZE];
typedef void (*KeyCopyF)(KeyType *kdest, KeyType ksrc); typedef void (*ValCopyF)(ValType *vdest, ValType vsrc); typedef unsigned (*KeyHashF)( KeyType key, int upperBound ); typedef int (*KeyCmprF)(KeyType key1, KeyType key2);
void HashAddH( KeyType key, ValType value,
KeyCopyF copyKey, ValCopyF copyVal, KeyHashF hashKey, KeyCmprF keySame )
{
unsigned hix = (*hashKey)(key, HASH_SIZE); MapEntry m_ent;
for (m_ent= hash[hix].first; m_ent && !(*keySame)(m_ent->key,key); m_ent=m_ent->link); if (m_ent) { (*copyVal)(&m_ent->value, value); } else { MapEntry last; MapEntry hme = (MapEntry)malloc(sizeof(struct sHme)); (*copyKey)(&hme->key, key); (*copyVal)(&hme->value, value); hme->link = NULL; last = hash[hix].last; if (last) {
// printf("Dup. hash key\n");
last->link = hme; } else hash[hix].first = hme; hash[hix].last = hme; }
}
int HashGetH(ValType *val, KeyType key, KeyHashF hashKey, KeyCmprF keySame ) {
unsigned hix = (*hashKey)(key, HASH_SIZE); MapEntry m_ent; for (m_ent= hash[hix].first; m_ent && !(*keySame)(m_ent->key,key); m_ent=m_ent->link); if (m_ent) { *val = m_ent->value; } return (m_ent != NULL);
}
void copyStr(const char**dest, const char *src) {
*dest = strdup(src);
} void copyInt( int *dest, int src) {
*dest = src;
} int strCompare( const char *key1, const char *key2) {
return strcmp(key1, key2) == 0;
}
void HashAdd( KeyType key, ValType value ) {
HashAddH( key, value, ©Str, ©Int, &strhashkey, &strCompare);
}
int HashGet(ValType *val, KeyType key) {
return HashGetH( val, key, &strhashkey, &strCompare);
}
int main() {
static const char * keyList[] = {"red","orange","yellow","green", "blue", "violet" }; static int valuList[] = {1,43,640, 747, 42, 42}; int ix;
for (ix=0; ix<6; ix++) { HashAdd(keyList[ix], valuList[ix]); } return 0;
}</lang>
C++
By strict definition a std::map is not a hash, but it provides the same functionality. The C++-200x update to the C++ standard is incorporating hashes. When they are standardized the code below can change std::map to std::unordered_map and this will technically be a hash table. The core idea, turning two sequences into an associative mapping, is valid either way.
<lang cpp>#include <map>
- include <string>
int main( int argc, char* argv[] ) {
std::string keys[] = { "1", "2", "3" } ; std::string vals[] = { "a", "b", "c" } ; std::map< std::string, std::string > hash ; for( int i = 0 ; i < 3 ; i++ ) { hash[ keys[i] ] = vals[i] ; }
}</lang>
Alternatively: <lang cpp>#include <map> // for std::map
- include <algorithm> // for std::transform
- include <string> // for std::string
- include <utility> // for std::make_pair
int main() {
std::string keys[] = { "one", "two", "three" }; std::string vals[] = { "foo", "bar", "baz" };
std::map<std::string, std::string> hash;
std::transform(keys, keys+3, vals, std::inserter(hash, hash.end()), std::make_pair<std::string, std::string>);
}</lang>
C#
<lang csharp>System.Collections.HashTable h = new System.Collections.HashTable();
string[] arg_keys = {"foo","bar","val"}; string[] arg_values = {"little", "miss", "muffet"};
//Some basic error checking int arg_length = 0; if ( arg_keys.Length == arg_values.Length ) {
arg_length = arg_keys.Length;
}
for( int i = 0; i < arg_length; i++ ){
h.add( arg_keys[i], arg_values[i] );
}</lang>
Alternate way of adding values
<lang csharp>for( int i = 0; i < arg_length; i++ ){
h[ arg_keys[i] ] = arg_values[i];
}</lang>
Clojure
<lang lisp>(zipmap [\a \b \c] [1 2 3])</lang>
Common Lisp
<lang lisp>(defun rosetta-code-hash-from-two-arrays (vector-1 vector-2 &key (test 'eql))
(assert (= (length vector-1) (length vector-2))) (let ((table (make-hash-table :test test :size (length vector-1)))) (map nil (lambda (k v) (setf (gethash k table) v)) vector-1 vector-2) table))</lang>
Or, using cl:loop:
<lang lisp>(defun rosetta-code-hash-from-two-arrays (vector-1 vector-2 &key (test 'eql))
(loop initially (assert (= (length vector-1) (length vector-2))) with table = (make-hash-table :test test :size (length vector-1)) for k across vector-1 for v across vector-2 do (setf (gethash k table) v) finally (return table)))</lang>
In Common Lisp terminology, a vector is a one-dimensional array.
D
<lang d>string[] keys = ["one", "two", "three"] int[] values = [1, 2, 3];
int[string] hash;
foreach(idx, key; keys)
hash[key] = values[idx];</lang>
E
<lang e>def keys := ["one", "two", "three"] def values := [1, 2, 3] __makeMap.fromColumns(keys, values)</lang>
F#
<lang fsharp> HashMultiMap(Array.zip [|"foo"; "bar"; "baz"|] [|16384; 32768; 65536|]) </lang>
Factor
<lang factor>USING: hashtables ; { "one" "two" "three" } { 1 2 3 } zip >hashtable</lang>
Falcon
<lang falcon> keys = [ 'a', 'b', 'c', 'd' ] values = [ 1, 2, 3, 4 ] hash = [ => ] for i in [ 0 : keys.len() ]: hash[ keys[ i ] ] = values[ i ] </lang>
Groovy
<lang groovy>keys = ['a','b','c'] vals = ['aaa', 'bbb', 'ccc'] hash = [:] i = 0 keys.each { entry ->
hash.put(entry, vals[i++])
}</lang>
Haskell
<lang haskell>import Data.Map
makeMap ks vs = fromList $ zip ks vs mymap = makeMap ['a','b','c'] [1,2,3]</lang>
Ioke
<lang ioke>{} addKeysAndValues([:a, :b, :c], [1, 2, 3])</lang>
J
Solution: <lang j>hash=: vals {~ keys&i.</lang> For example:
<lang j> keys=: 10?.100
vals=: > ;:'zero one two three four five six seven eight nine' hash=: vals {~ keys&i.
keys
46 99 23 62 42 44 12 5 68 63
$vals
10 5
hash 46
zero
hash 99
one
hash 63 5 12 5 23
nine
seven
six
seven
two</lang>
Here, keys
is a list of 10 integers between 0 and 99 chosen at random without repetition, and vals
is a 10 by 5 character matrix.
Java
<lang java>import java.util.HashMap; public static void main(String[] args){ String[] keys= {"a", "b", "c"}; int[] vals= {1, 2, 3}; HashMap<String, Integer> hash= new HashMap<String, Integer>();
for(int i= 0; i < keys.length; i++){ hash.put(keys[i], vals[i]); } }</lang>
JavaScript
<lang javascript>var keys = ['a', 'b', 'c']; var values = [1, 2, 3]; var map = {}; for(var i in keys) {
map[ keys[i] ] = values[i];
}</lang>
Objective-C
<lang objc>NSArray *keys = [NSArray arrayWithObjects:@"a", @"b", @"c", nil]; NSArray *values = [NSArray arrayWithObjects:[NSNumber numberWithInt:1],
[NSNumber numberWithInt:2], [NSNumber numberWithInt:3], nil];
NSDictionary *dict = [NSDictionary dictionaryWithObjects:values forKeys:keys];</lang>
OCaml
The idiomatic solution uses lists rather than arrays.
<lang ocaml>let keys = [ "foo"; "bar"; "baz" ] and vals = [ 16384; 32768; 65536 ] and hash = Hashtbl.create 0;;
List.iter2 (Hashtbl.add hash) keys vals;;</lang>
In the extremely unlikely event that it was actually necessary to use arrays, the solution would become slightly less elegant: (except using the ExtLib which provides the equivalent Array.iter2)
<lang ocaml>let keys = [| "foo"; "bar"; "baz" |] and vals = [| 16384; 32768; 65536 |] and hash = Hashtbl.create 0;;
for i = 0 to Array.length keys - 1 do
Hashtbl.add hash keys.(i) vals.(i)
done;;</lang>
In either case, an exception is raised if the inputs are different lengths.
If you want to use functional binary search trees instead of hash tables:
<lang ocaml>module StringMap = Map.Make (String);;
let keys = [ "foo"; "bar"; "baz" ] and vals = [ 16384; 32768; 65536 ] and map = StringMap.empty;;
let map = List.fold_right2 StringMap.add keys vals map;;</lang>
Oz
<lang oz>declare
fun {ZipRecord Keys Values} {List.toRecord unit {List.zip Keys Values MakePair}} end
fun {MakePair A B} A#B end
in
{Show {ZipRecord [a b c] [1 2 3]}}</lang>
Perl
<lang perl>my @keys = qw(a b c); my @vals = (1, 2, 3); my %hash; @hash{@keys} = @vals;</lang>
Alternatively, using
:
<lang perl>use List::MoreUtils qw(zip); my %hash = zip @keys, @vals;</lang>
Perl 6
<lang perl6>my @keys = <a b c d e>; my @vals = ^5; my %hash = @keys Z @vals;</lang>
Alternatively:
<lang perl6>my %hash; %hash{@keys} = @vals;</lang>
PHP
<lang php>$keys = array('a', 'b', 'c'); $values = array(1, 2, 3); $hash = array_combine($keys, $values);</lang>
<lang php>$keys = array('a', 'b', 'c'); $values = array(1, 2, 3); $hash = array(); for ($idx = 0; $idx < count($keys); $idx++) {
$hash[$keys[$idx]] = $values[$idx];
}</lang>
Pop11
<lang pop11>vars keys = { 1 a b c}; vars vals = { 2 3 valb valc}; vars i;
- Create hash table
vars ht = newmapping([], 500, 0, true);
- Loop over input arrays (vectors)
for i from 1 to length(keys) do
vals(i) -> ht(keys(i));
endfor;</lang>
PowerShell
<lang powershell>function create_hash ([array] $keys, [array] $values) {
$h = @{} if ($keys.Length -ne $values.Length) { Write-Error -Message "Array lengths do not match" ` -Category InvalidData ` -TargetObject $values } else { for ($i = 0; $i -lt $keys.Length; $i++) { $h[$keys[$i]] = $values[$i] } } return $h
}</lang>
Prolog
<lang prolog>% this one with side effect hash table creation
- -dynamic hash/2.
make_hash([],[]). make_hash([H|Q],[H1|Q1]):- assert(hash(H,H1)), make_hash(Q,Q1).
- -make_hash([un,deux,trois],[[a,b,c],[d,e,f],[g,h,i]])
% this one without side effects
make_hash_pure([],[],[]). make_hash_pure([H|Q],[H1|Q1],[hash(H,H1)|R]):- make_hash_pure(Q,Q1,R).
- -make_hash_pure([un,deux,trois],[[a,b,c],[d,e,f],[g,h,i]],L),findall(M,(member(M,L),assert(M)),L).</lang>
PureBasic
<lang PureBasic>Dim keys.s(3) Dim vals.s(3) NewMap Hash.s()
keys(0)="a" : keys(1)="b" : keys(2)="c" : keys(3)="d" vals(0)="1" : vals(1)="2" : vals(2)="3" : vals(3)="4" For n = 0 To 3
Hash(keys(n))= vals(n)
Next ForEach Hash()
Debug Hash()
Next</lang>
Python
<lang python>keys = ['a', 'b', 'c'] values = [1, 2, 3] hash = dict(zip(keys, values))
- Lazily:
from itertools import izip hash = dict(izip(keys, values))</lang>
Shows off the dict comprehensions in Python 3: <lang python>keys = ['a', 'b', 'c'] values = [1, 2, 3] hash = {key: value for key, value in zip(keys, values)}</lang>
(any version)
<lang python>keys = ['a', 'b', 'c'] values = [1, 2, 3] hash = {} for i range(len(keys)):
hash[keys[i]] = values[i]</lang>
The original (Ruby) example uses a range of different types as keys. Here is similar in python (run at the shell): <lang python>>>> class Hashable(object): def __hash__(self): return id(self) ^ 0xBEEF
>>> my_inst = Hashable()
>>> my_int = 1
>>> my_complex = 0 + 1j
>>> my_float = 1.2
>>> my_string = "Spam"
>>> my_bool = True
>>> my_unicode = u'Ham'
>>> my_list = ['a', 7]
>>> my_tuple = ( 0.0, 1.4 )
>>> my_set = set(my_list)
>>> def my_func():
pass
>>> class my_class(object): pass
>>> keys = [my_inst, my_tuple, my_int, my_complex, my_float, my_string, my_bool, my_unicode, frozenset(my_set), tuple(my_list), my_func, my_class] >>> values = range(12) >>> d = dict(zip(keys, values)) >>> for key, value in d.items(): print key, ":", value
1 : 6 1j : 3 Ham : 7 Spam : 5 (0.0, 1.3999999999999999) : 1 frozenset(['a', 7]) : 8 1.2 : 4 ('a', 7) : 9 <function my_func at 0x0128E7B0> : 10 <class '__main__.my_class'> : 11 <__main__.Hashable object at 0x012AFC50> : 0 >>></lang>
R
Assuming that the keys are coercible to character form, we can simply use the names attribute to create a hash. This example is taken from the Wikipedia page on hash tables. <lang r># Set up hash table keys <- c("John Smith", "Lisa Smith", "Sam Doe", "Sandra Dee", "Ted Baker") values <- c(152, 1, 254, 152, 153) names(values) <- keys
- Get value corresponding to a key
values["Sam Doe"] # vals["Sam Doe"]
- Get all keys corresponding to a value
names(values)[values==152] # "John Smith" "Sandra Dee"</lang>
Raven
<lang raven>[ 'a' 'b' 'c' ] as $keys [ 1 2 3 ] as $vals $keys $vals combine as $hash</lang>
Ruby
<lang ruby>keys=['hal',666,[1,2,3]] vals=['ibm','devil',123] hash = Hash[keys.zip(vals)] # Ruby 1.8.7 and later hash = Hash[*keys.zip(vals).flatten] # pre-1.8.7
- now hash => {'hal' => 'ibm', 666 => 'devil', [1,2,3] => 123}
- retrieve the value linked to the key [1,2,3]
puts hash[ [1,2,3] ]
- 123</lang>
Scala
<lang scala>val keys = Array(1, 2, 3) val values = Array("A", "B", "C") val map = Map(keys.zip(values) : _*) // returns Map(1 -> "A", 2 -> "B", 3 -> "C") // keys.zip(values) is an array of pairs : Array((1, "A"), (2, "B"), (3, "C")) // Map(...) expects multiple pairs arguments. Syntax ": _*" tells the single argument contains multiple values.</lang>
Scheme
Using SRFI 69: <lang scheme>(define (lists->hash-table keys values . rest)
(apply alist->hash-table (map cons keys values) rest))</lang>
Seed7
<lang seed7>$ include "seed7_05.s7i";
const type: numericHash is hash [string] integer; var numericHash: myHash is numericHash.value;
const proc: main is func
local var array string: keyList is [] ("one", "two", "three"); var array integer: valueList is [] (1, 2, 3); var integer: number is 0; begin for number range 1 to length(keyList) do myHash @:= [keyList[number]] valueList[number]; end for; end func;</lang>
Standard ML
Using functional binary search trees instead of hash tables:
<lang sml>structure StringMap = BinaryMapFn (struct
type ord_key = string val compare = String.compare end);
val keys = [ "foo", "bar", "baz" ] and vals = [ 16384, 32768, 65536 ] and myMap = StringMap.empty;
val myMap = foldl StringMap.insert' myMap (ListPair.zipEq (keys, vals));</lang>
Using hash tables:
<lang sml>exception NotFound;
val keys = [ "foo", "bar", "baz" ] and vals = [ 16384, 32768, 65536 ] and hash = HashTable.mkTable (HashString.hashString, op=) (42, NotFound);
ListPair.appEq (HashTable.insert hash) (keys, vals);</lang>
Tcl
Arrays in Tcl are automatically associative, i.e. there are no "not hashed arrays". If we can take "arrays of equal length" to mean "lists of equal length", then the task might look like this: <lang tcl>set keys [list fred bob joe] set values [list barber plumber tailor] array set arr {} foreach a $keys b $values { set arr($a) $b }</lang> Alternatively, a dictionary could be used: <lang tcl>foreach a $keys b $values {
dict set jobs $a $b
}</lang>
UnixPipes
Using a sorted file as an associative array (see Creating an associative array for usage.)
<lang bash>cat <<VAL >p.values apple boy cow dog elephant VAL
cat <<KEYS >p.keys a b c d e KEYS
paste -d\ <(cat p.values | sort) <(cat p.keys | sort)</lang>
Ursala
There's a built in operator for this. <lang Ursala>keys = <'foo','bar','baz'> values = <12354,145430,76748>
hash_function = keys-$values</lang> test program: <lang Ursala>#cast %nL
test = hash_function* <'bar','baz','foo','bar'></lang> output:
<145430,76748,12354,145430>
VBScript
VBScript (and Visual Basic in general) calls hashes "dictionary objects".
<lang vbscript>Set dict = CreateObject("Scripting.Dictionary") os = Array("Windows", "Linux", "MacOS") owner = Array("Microsoft", "Linus Torvalds", "Apple") For n = 0 To 2
dict.Add os(n), owner(n)
Next MsgBox dict.Item("Linux") MsgBox dict.Item("MacOS") MsgBox dict.Item("Windows")</lang>
Output:
Linus Torvalds Apple Microsoft
Visual Basic
The VBScript version can be used in Visual Basic unchanged, but this version explicitly declares dict
as a dictionary, rather than setting a Variant to a Dictionary object.
Normally, I prefer to explicitly declare all variables, and I strongly dislike variants, but in this instance variants are apparently required, because Array()
doesn't like anything else. (In a real program, I probably wouldn't load the arrays with Array()
, therefore allowing me to declare those arrays as strings, but it was a simple expendiant for this example.)
<lang vb>Dim dict As New Dictionary os = Array("Windows", "Linux", "MacOS") owner = Array("Microsoft", "Linus Torvalds", "Apple") For n = 0 To 2
dict.Add os(n), owner(n)
Next Debug.Print dict.Item("Linux") Debug.Print dict.Item("MacOS") Debug.Print dict.Item("Windows")</lang>
Visual Basic .NET
<lang vbnet>Dim names = New String() {"Frank", "Tom", "Jones"} Dim grades = New Integer() {90, 87, 96}
Dim hash = New Dictionary(Of String, Integer)
For i = 0 To names.Length - 1
hash.Add(names(i), grades(i))
Next</lang>
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