Associative array/Merging

Associative array/Merging
You are encouraged to solve this task according to the task description, using any language you may know.

Task

Define two associative arrays, where one represents the following "base" data:

Key	Value
"name"	"Rocket Skates"
"price"	12.75
"color"	"yellow"

And the other represents "update" data:

Key	Value
"price"	15.25
"color"	"red"
"year"	1974

Merge these into a new associative array that contains every key found in either of the source ones. Each key should map to the value in the second (update) table if that exists, or else to the value in the first (base) table. If possible, do this in a way that does not mutate the original two associative arrays. Obviously this should be done in a way that would work for any data, not just the specific data given here, but in this example the result should be:

Key	Value
"name"	"Rocket Skates"
"price"	15.25
"color"	"red"
"year"	1974

ALGOL 68

Works with: ALGOL 68G version Any - tested with release 2.8.3.win32

Uses the associative array implementations in ALGOL_68/prelude. <lang algol68># associative array merging #

1. the modes allowed as associative array element values - change to suit #

MODE AAVALUE = UNION( STRING, INT, REAL );

1. the modes allowed as associative array element keys - change to suit #

MODE AAKEY = STRING;

1. include the associative array code #

PR read "aArrayBase.a68" PR

1. adds or replaces all elements from b into a #

PRIO UPDATE = 9; OP UPDATE = ( REF AARRAY a, REF AARRAY b )REF AARRAY: BEGIN

   REF AAELEMENT e := FIRST b;
   WHILE e ISNT nil element DO
       a // key OF e := value OF e;
       e := NEXT b
   OD;
   a

END # UPDATE # ;

1. construct the associative arrays for the task #

REF AARRAY a := INIT LOC AARRAY; REF AARRAY b := INIT LOC AARRAY; a // "name"  := "Rocket Skates"; a // "price" := 12.75; a // "color" := "yellow"; b // "price" := 15.25; b // "color" := "red"; b // "year"  := 1974;

1. merge the arrays #

REF AARRAY c := INIT LOC AARRAY; c UPDATE a UPDATE b;

1. show the merged array #

REF AAELEMENT e := FIRST c; WHILE e ISNT nil element DO

   print( ( key OF e
          , ": "
          , CASE value OF e
              IN (STRING s): s
               , (INT    i): whole( i, 0 )
               , (REAL   r): fixed( r, -12, 2 )
             OUT "????"
            ESAC
          , newline
          )
        );
   e := NEXT c

OD</lang>

Output:

name: Rocket Skates
year: 1974
price:        15.25
color: red

AWK

<lang AWK>

1. syntax: GAWK -f ASSOCIATIVE_ARRAY_MERGING.AWK
3. sorting:
4. PROCINFO["sorted_in"] is used by GAWK
5. SORTTYPE is used by Thompson Automation's TAWK

BEGIN {

   PROCINFO["sorted_in"] = "@ind_str_asc" ; SORTTYPE = 1
   arr1["name"] = "Rocket Skates"
   arr1["price"] = "12.75"
   arr1["color"] = "yellow"
   show_array(arr1,"base")
   arr2["price"] = "15.25"
   arr2["color"] = "red"
   arr2["year"] = "1974"
   show_array(arr2,"update")
   for (i in arr1) { arr3[i] = arr1[i] }
   for (i in arr2) { arr3[i] = arr2[i] }
   show_array(arr3,"merged")
   exit(0)

} function show_array(arr,desc, i) {

   printf("\n%s array\n",desc)
   for (i in arr) {
     printf("%-5s : %s\n",i,arr[i])
   }

} </lang>

Output:

base array
color : yellow
name  : Rocket Skates
price : 12.75

update array
color : red
price : 15.25
year  : 1974

merged array
color : red
name  : Rocket Skates
price : 15.25
year  : 1974

C++

<lang cpp>#include <iostream>

1. include <string>
2. include <map>

template<typename map_type> map_type merge(const map_type& original, const map_type& update) {

   map_type result(update);
   result.insert(original.begin(), original.end());
   return result;

}

int main() {

   typedef std::map<std::string, std::string> map;
   map original{
       {"name", "Rocket Skates"},
       {"price", "12.75"},
       {"color", "yellow"}
   };
   map update{
       {"price", "15.25"},
       {"color", "red"},
       {"year", "1974"}
   };
   map merged(merge(original, update));
   for (auto&& i : merged)
       std::cout << "key: " << i.first << ", value: " << i.second << '\n';
   return 0;

}</lang>

Output:

key: color, value: red
key: name, value: Rocket Skates
key: price, value: 15.25
key: year, value: 1974

Dart

<lang javascript> main() { var base = { 'name': 'Rocket Skates', 'price': 12.75, 'color': 'yellow' };

var newData = { 'price': 15.25, 'color': 'red', 'year': 1974 };

var updated = Map.from( base ) // create new Map from base ..addAll( newData ); // use cascade operator to add all new data

assert( base.toString() == '{name: Rocket Skates, price: 12.75, color: yellow}' ); assert( updated.toString() == '{name: Rocket Skates, price: 15.25, color: red, year: 1974}');

} </lang>

F#

<lang fsharp> type N = |Price of float|Name of string|Year of int|Colour of string let n=Map<string,N>[("name",Name("Rocket Skates"));("price",Price(12.75));("colour",Colour("yellow"))] let g=Map<string,N>[("price",Price(15.25));("colour",Colour("red"));("year",Year(1974))] let ng=(Map.toList n)@(Map.toList g)|>Map.ofList printfn "%A" ng </lang>

Output:

map
  [("colour", Colour "red"); ("name", Name "Rocket Skates");
   ("price", Price 15.25); ("year", Year 1974)]

// Minimum positive multiple in base 10 using only 0 and 1. Nigel Galloway: March 9th., 2020

Factor

The assoc-union word does this. assoc-union! is a variant that mutates the first associative array.

Works with: Factor version 0.99 2019-10-06

<lang factor>USING: assocs prettyprint ;

{ { "name" "Rocket Skates" } { "price" 12.75 } { "color" "yellow" } } { { "price" 15.25 } { "color" "red" } { "year" 1974 } } assoc-union .</lang>

Output:

V{
    { "name" "Rocket Skates" }
    { "price" 15.25 }
    { "color" "red" }
    { "year" 1974 }
}

Go

<lang go>package main

import "fmt"

type assoc map[string]interface{}

func merge(base, update assoc) assoc {

   result := make(assoc)
   for k, v := range base {
       result[k] = v
   }
   for k, v := range update {
       result[k] = v
   }
   return result

}

func main() {

   base := assoc{"name": "Rocket Skates", "price": 12.75, "color": "yellow"}
   update := assoc{"price": 15.25, "color": "red", "year": 1974}
   result := merge(base, update)
   fmt.Println(result)

}</lang>

Output:

map[color:red name:Rocket Skates price:15.25 year:1974]

Haskell

There are various approaches, all of which would be strictly typed.
For example, if we want to treat the input and output records as all sharing the same type: <lang haskell>data Item = Item

 { name :: Maybe String
 , price :: Maybe Float
 , color :: Maybe String
 , year :: Maybe Int
 } deriving (Show)

itemFromMerge :: Item -> Item -> Item itemFromMerge (Item n p c y) (Item n1 p1 c1 y1) =

 Item (maybe n pure n1) (maybe p pure p1) (maybe c pure c1) (maybe y pure y1)

main :: IO () main =

 print $
 itemFromMerge
   (Item (Just "Rocket Skates") (Just 12.75) (Just "yellow") Nothing)
   (Item Nothing (Just 15.25) (Just "red") (Just 1974))</lang>

Output:

Item {name = Just "Rocket Skates", price = Just 15.25, color = Just "red", year = Just 1974}

Icon and Unicon

<lang unicon>procedure main()

   local base, update, master, f, k

   base := table()
   base["name"] := "Rocket Skates"
   base["price"] := 12.75
   base["color"] := "yellow"

   update := table()
   update["price"] := 15.25
   update["color"] := "red"
   update["year"] := 1974

   master := table()
   every k := key((f := base | update)) do {
       master[k] := f[k]
   }

   every k := key(master) do {
       write(k, " = ", master[k])
   }

end</lang>

Output:

prompt$ unicon -s merge.icn -x
color = red
name = Rocket Skates
price = 15.25
year = 1974

J

<lang J> merge=: ,. NB. use: update merge original compress=: #"1~ ~:@:keys keys=: {. values=: {: get=: [: > ((i.~ keys)~ <)~ { values@:] NB. key get (associative array) pair=: [: |: <;._2;._2 </lang> Exercise the definitions. Interactive J prompts with 3 space indentation.

   ] D=: pair 0 :0
name;Rocket Skates;
price;12.75;
color;yellow;
)
┌─────────────┬─────┬──────┐
│name         │price│color │
├─────────────┼─────┼──────┤
│Rocket Skates│12.75│yellow│
└─────────────┴─────┴──────┘

   E=: pair 0 :0
price;15.25;
color;red;
year;1974;
)

   'color'get D
yellow

   'color'get E
red

   ] F=: E merge D
┌─────┬─────┬────┬─────────────┬─────┬──────┐
│price│color│year│name         │price│color │
├─────┼─────┼────┼─────────────┼─────┼──────┤
│15.25│red  │1974│Rocket Skates│12.75│yellow│
└─────┴─────┴────┴─────────────┴─────┴──────┘

   'color' get F
red

   ]G=: compress F
┌─────┬─────┬────┬─────────────┐
│price│color│year│name         │
├─────┼─────┼────┼─────────────┤
│15.25│red  │1974│Rocket Skates│
└─────┴─────┴────┴─────────────┘

   'no such key'get F
|index error: get
|   'no such key'    get F

   'color'get F
red

Java

<lang java>import java.util.*;

class MergeMaps {

   public static void main(String[] args) {
       Map<String, Object> base = new HashMap<>();
       base.put("name", "Rocket Skates");
       base.put("price", 12.75);
       base.put("color", "yellow");
       Map<String, Object> update = new HashMap<>();
       update.put("price", 15.25);
       update.put("color", "red");
       update.put("year", 1974);

       Map<String, Object> result = new HashMap<>(base);
       result.putAll(update);

       System.out.println(result);
   }

}</lang>

Output:

{name=Rocket Skates, color=red, year=1974, price=15.25}

JavaScript

<lang javascript>(() => {

   'use strict';

   console.log(JSON.stringify(
       Object.assign({}, // Fresh dictionary.
           { // Base.
               "name": "Rocket Skates",
               "price": 12.75,
               "color": "yellow"
           }, { // Update.
               "price": 15.25,
               "color": "red",
               "year": 1974
           }
       ), 
       null, 2
   ))

})();</lang>

Output:

{
  "name": "Rocket Skates",
  "price": 15.25,
  "color": "red",
  "year": 1974
}

Julia

julia> dict1 = Dict("name" => "Rocket Skates", "price" => 12.75, "color" => "yellow")
Dict{String,Any} with 3 entries:
  "name"  => "Rocket Skates"
  "price" => 12.75
  "color" => "yellow"

julia> dict2 = Dict("price" => 15.25, "color" => "red", "year" => 1974)
Dict{String,Any} with 3 entries:
  "price" => 15.25
  "year"  => 1974
  "color" => "red"

julia> merge(dict1, dict2)
Dict{String,Any} with 4 entries:
  "name"  => "Rocket Skates"
  "price" => 15.25
  "year"  => 1974
  "color" => "red"

julia> merge(dict2, dict1)
Dict{String,Any} with 4 entries:
  "name"  => "Rocket Skates"
  "price" => 12.75
  "year"  => 1974
  "color" => "yellow"

julia> union(dict1, dict2)
6-element Array{Pair{String,Any},1}:
  "name" => "Rocket Skates"
 "price" => 12.75
 "color" => "yellow"
 "price" => 15.25
  "year" => 1974
 "color" => "red"

Kotlin

<lang scala> fun main() {

   val base = HashMap<String,String>()
   val update =  HashMap<String,String>()

   base["name"] = "Rocket Skates"
   base["price"] = "12.75"
   base["color"] = "yellow"

   update["price"] = "15.25"
   update["color"] = "red"
   update["year"] = "1974"

   val merged = HashMap(base)
   merged.putAll(update)

   println("base: $base")
   println("update: $update")
   println("merged: $merged")

} </lang>

Output:

base: {color=yellow, price=12.75, name=Rocket Skates}
update: {color=red, year=1974, price=15.25}
merged: {name=Rocket Skates, color=red, year=1974, price=15.25}

Lua

<lang Lua>base = {name="Rocket Skates", price=12.75, color="yellow"} update = {price=15.25, color="red", year=1974}

--clone the base data -- result = {} for key,val in pairs(base) do

   result[key] = val

end

--copy in the update data -- for key,val in pairs(update) do

   result[key] = val

end

--print the result -- for key,val in pairs(result) do

   print(string.format("%s: %s", key, val))

end</lang>

Output:

price: 15.25
color: red
year: 1974
name: Rocket Skates

MiniScript

MiniScript supports merging maps with the + operator. <lang MiniScript>base = {"name":"Rocket Skates", "price":12.75, "color":"yellow"} update = {"price":15.25, "color":"red", "year":1974}

result = base + update

print result</lang>

Output:

{"color": "red", "name": "Rocket Skates", "price": 15.25, "year": 1974}

Objective-C

Works with: Cocoa

<lang objc>#import <Foundation/Foundation.h>

int main(void) {

 @autoreleasepool {
   NSDictionary *base = @{@"name": @"Rocket Skates", @"price": @12.75, @"color": @"yellow"};
   NSDictionary *update = @{@"price": @15.25, @"color": @"red", @"year": @1974};
   
   NSMutableDictionary *result = [[NSMutableDictionary alloc] initWithDictionary:base];
   [result addEntriesFromDictionary:update];
   
   NSLog(@"%@", result);
 }
 return 0;

}</lang>

Output:

{
    color = red;
    name = "Rocket Skates";
    price = "15.25";
    year = 1974;
}

Perl

<lang perl>use strict; use warnings;

my %base = ("name" => "Rocket Skates", "price" => 12.75, "color" => "yellow"); my %more = ("price" => 15.25, "color" => "red", "year" => 1974);

print "Update\n"; my %update = (%base, %more); printf "%-7s %s\n", $_, $update{$_} for sort keys %update;

print "\nMerge\n"; my %merge; $merge{$_} = [$base{$_}] for keys %base; push @{$merge{$_}}, $more{$_} for keys %more; printf "%-7s %s\n", $_, join ', ', @{$merge{$_}} for sort keys %merge;</lang>

Output:

Update
color   red
name    Rocket Skates
price   15.25
year    1974

Merge
color   yellow, red
name    Rocket Skates
price   12.75, 15.25
year    1974

Phix

<lang Phix>integer d1 = new_dict({{"name","Rocket Skates"},{"price",12.75},{"color","yellow"}}),

       d2 = new_dict({{"price",15.25},{"color","red"},{"year",1974}}),
       d3 = new_dict(d1)

function merger(object key, data, /*user_data*/) setd(key,data,d3) return 1 end function traverse_dict(merger,NULL,d2) include builtins/map.e ?pairs(d3)</lang>

Output:

{{"color","red"},{"name","Rocket Skates"},{"price",15.25},{"year",1974}}

PHP

<lang php><? $base = array("name" => "Rocket Skates", "price" => 12.75, "color" => "yellow"); $update = array("price" => 15.25, "color" => "red", "year" => 1974);

$result = $update + $base; // Notice that the order is reversed print_r($result); ?></lang>

Output:

Array
(
    [price] => 15.25
    [color] => red
    [year] => 1974
    [name] => Rocket Skates
)

Alternative: <lang php><? $base = array("name" => "Rocket Skates", "price" => 12.75, "color" => "yellow"); $update = array("price" => 15.25, "color" => "red", "year" => 1974);

$result = array_merge($base, $update); print_r($result); ?></lang>

Output:

Array
(
    [name] => Rocket Skates
    [price] => 15.25
    [color] => red
    [year] => 1974
)

Python

As of Python 3.5, this can be solved with the dictionary unpacking operator.

Works with: Python version 3.5+

<lang Python>base = {"name":"Rocket Skates", "price":12.75, "color":"yellow"} update = {"price":15.25, "color":"red", "year":1974}

result = {**base, **update}

print(result)</lang>

Output:

{'name': 'Rocket Skates', 'price': 15.25, 'color': 'red', 'year': 1974}

Alternative: <lang Python>base = {"name":"Rocket Skates", "price":12.75, "color":"yellow"} update = {"price":15.25, "color":"red", "year":1974}

result = base.copy() result.update(update)

print(result)</lang>

Output:

{'name': 'Rocket Skates', 'price': 15.25, 'color': 'red', 'year': 1974}

Raku

(formerly Perl 6)

Works with: Rakudo version 2019.11

I must say I somewhat disagree with the terminology. The requested operation is an update not a merge. Demonstrate both an update and a merge. Associative arrays are commonly called hashes in Raku.

<lang perl6># Show original hashes say my %base = :name('Rocket Skates'), :price<12.75>, :color<yellow>; say my %update = :price<15.25>, :color<red>, :year<1974>;

1. Need to assign to anonymous hash to get the desired results and avoid mutating
2. TIMTOWTDI

say "\nUpdate:\n", join "\n", sort %=%base, %update;

1. Same

say "\nUpdate:\n", {%base, %update}.sort.join: "\n";

say "\nMerge:\n", join "\n", sort ((%=%base).push: %update)».join: ', ';

1. Same

say "\nMerge:\n", ({%base}.push: %update)».join(', ').sort.join: "\n";

1. Demonstrate unmutated hashes

say "\n", %base, "\n", %update;</lang>

Output:

{color => yellow, name => Rocket Skates, price => 12.75}
{color => red, price => 15.25, year => 1974}

Update:
color	red
name	Rocket Skates
price	15.25
year	1974

Update:
color	red
name	Rocket Skates
price	15.25
year	1974

Merge:
color	yellow, red
name	Rocket Skates
price	12.75, 15.25
year	1974

Merge:
color	yellow, red
name	Rocket Skates
price	12.75, 15.25
year	1974

{color => yellow, name => Rocket Skates, price => 12.75}
{color => red, price => 15.25, year => 1974}

REXX

The REXX language has no native support to acquire the keys of an associate array after they have been defined,  
so it must be performed at definition time,   but there are function packages to perform this function.

Some extra coding was added to support adjustable (maximum) widths for the displaying of the associate array names, keys, and values.

The double quotes that surround the string (character) items (as shown in the task's preamble) weren't included for this presentation,
although they could easily be added. <lang rexx>/*REXX program merges two associative arrays (requiring an external list of indices). */ $.= /*define default value(s) for arrays. */ @.wAAn= 21; @.wKey= 7; @.wVal= 7 /*max widths of: AAname, keys, values.*/ call defAA 'base', "name Rocket Skates", 'price 12.75', "color yellow" call defAA 'update', "price 15.25", "color red", 'year 1974' call show 'base' call show 'update' call show 'new' exit /*stick a fork in it, we're all done. */ /*──────────────────────────────────────────────────────────────────────────────────────*/ defAA: procedure expose $. @.; parse arg AAn; new= 'new' /*get AA name; set NEW.*/

        do j=2  to arg();   parse value arg(j)  with  key val   /*obtain key and value.*/
        $.AAn.key=val;                          /*assign a  value  to a  key for AAn.  */
        if wordpos(key, $.AAN.?keys)==0  then $.AAn.?keys=$.AAn.?keys key
                                                /* [↑]  add to key list if not in list.*/
        $.new.key=val                           /*assign a  value  to a  key for "new".*/
        if wordpos(key, $.new.?keys)==0  then $.new.?keys=$.new.?keys key
                                                /* [↑]  add to key list if not in list.*/
        @.wKey= max(@.wKey, length(key) )       /*find max width of a name of a  key.  */
        @.wVal= max(@.wVal, length(val) )       /*  "   "    "    " "   "   " "  value.*/
        @.wAA = max(@.wAAn, length(AAn) )       /*  "   "    "    " "   "   "    array.*/
        end   /*j*/
      return

/*──────────────────────────────────────────────────────────────────────────────────────*/ show: procedure expose $. @.; parse arg AAn; say; _= '═' /*set title char.*/

        do j=1  for words($.AAn.?keys)                                /*process keys.  */
        if j==1  then say  center('associate array', @.wAAn,     _)  ,
                           center("key"            , @.wKey,     _)  ,
                           center('value'          , @.wVal + 2, _)
        key= word($.AAn.?keys, j)                              /*get the name of a key.*/
        say center(AAn, @.wAAn)  right(key, @.wKey)  $.AAn.key /*show some information.*/
        end   /*j*/
      return</lang>

output   when using the internal default inputs:

═══associate array═══ ══key══ ═════value═════
        base             name Rocket Skates
        base            price 12.75
        base            color yellow

═══associate array═══ ══key══ ═════value═════
       update           price 15.25
       update           color red
       update            year 1974

═══associate array═══ ══key══ ═════value═════
         new             name Rocket Skates
         new            price 15.25
         new            color red
         new             year 1974

Ruby

<lang ruby>base = {"name" => "Rocket Skates", "price" => 12.75, "color" => "yellow"} update = {"price" => 15.25, "color" => "red", "year" => 1974}

result = base.merge(update) p result</lang>

Output:

{"name"=>"Rocket Skates", "price"=>15.25, "color"=>"red", "year"=>1974}

Rust

<lang rust>use std::collections::HashMap;

fn main() {

   let mut original = HashMap::new();
   original.insert("name", "Rocket Skates");
   original.insert("price", "12.75");
   original.insert("color", "yellow");

   let mut update = HashMap::new();
   update.insert("price", "15.25");
   update.insert("color", "red");
   update.insert("year", "1974");

   original.extend(&update);

   println!("{:#?}", original);

} </lang>

Output:

{
    "name": "Rocket Skates",
    "color": "red",
    "year": "1974",
    "price": "15.25",
}

Swift

Works with: Swift version 5+

<lang swift>let base : [String: Any] = ["name": "Rocket Skates", "price": 12.75, "color": "yellow"] let update : [String: Any] = ["price": 15.25, "color": "red", "year": 1974]

let result = base.merging(update) { (_, new) in new }

print(result)</lang>

Output:

["price": 15.25, "name": "Rocket Skates", "color": "red", "year": 1974]

zkl

<lang zkl>base:=Dictionary(

  "name", 	"Rocket Skates",
  "price", 	12.75,
  "color", 	"yellow",);

update:=Dictionary(

  "price", 	15.25,
  "color", 	"red",
  "year", 	1974,);

update.pump( new:=base.copy() );

new.pump(Void,fcn([(k,v)]){ println("%s\t%s".fmt(k,v)) });</lang>

Output:

price	15.25
color	red
year	1974
name	Rocket Skates