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Associative array/Merging

From Rosetta Code
Task
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



11l[edit]

Translation of: Python
V base = [‘name’ = ‘Rocket Skates’, ‘price’ = ‘12.75’, ‘color’ = ‘yellow’]
V update = [‘price’ = ‘15.25’, ‘color’ = ‘red’, ‘year’ = ‘1974’]
 
V result = copy(base)
result.update(update)
 
print(result)
Output:
[color = red, name = Rocket Skates, price = 15.25, year = 1974]

Ada[edit]

with Ada.Text_Io;
with Ada.Containers.Indefinite_Ordered_Maps;
 
procedure Merge_Maps is
use Ada.Text_Io;
 
type Key_Type is new String;
type Value_Type is new String;
 
package Maps is
new Ada.Containers.Indefinite_Ordered_Maps (Key_Type => Key_Type,
Element_Type => Value_Type);
use Maps;
 
function Merge (Original : Map; Update : Map) return Map is
Result : Map  := Original;
Cur  : Cursor := Update.First;
begin
while Has_Element (Cur) loop
if Original.Contains (Key (Cur)) then
Result.Replace_Element (Result.Find (Key (Cur)),
Element (Cur));
else
Result.Insert (Key (Cur), Element (Cur));
end if;
Next (Cur);
end loop;
return Result;
end Merge;
 
procedure Put_Map (M : Map) is
Cur : Cursor := M.First;
begin
while Has_Element (Cur) loop
Put (String (Key (Cur)));
Set_Col (12);
Put (String (Element (Cur)));
New_Line;
Next (Cur);
end loop;
end Put_Map;
 
Original : Map;
Update  : Map;
Result  : Map;
begin
Original.Insert ("name", "Rocket Skates");
Original.Insert ("price", "12.75");
Original.Insert ("color", "yellow");
 
Update.Insert ("price", "15.25");
Update.Insert ("color", "red");
Update.Insert ("year", "1974");
 
Result := Merge (Original, Update);
 
Put_Line ("Original:");
Put_Map (Original);
New_Line;
 
Put_Line ("Update:");
Put_Map (Update);
New_Line;
 
Put_Line ("Result of merge:");
Put_Map (Result);
New_Line;
 
end Merge_Maps;
Output:
Original:
color      yellow
name       Rocket Skates
price      12.75

Update:
color      red
price      15.25
year       1974

Result of merge:
color      red
name       Rocket Skates
price      15.25
year       1974

ALGOL 68[edit]

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

Uses the associative array implementations in ALGOL_68/prelude.

# associative array merging                                                  #
 
# the modes allowed as associative array element values - change to suit #
MODE AAVALUE = UNION( STRING, INT, REAL );
# the modes allowed as associative array element keys - change to suit #
MODE AAKEY = STRING;
# initial value for an array element #
AAVALUE init element value = "";
 
# include the associative array code #
PR read "aArrayBase.a68" PR
 
# 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 # ;
 
# 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;
# merge the arrays #
REF AARRAY c := INIT LOC AARRAY;
c UPDATE a UPDATE b;
# 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
Output:
name: Rocket Skates
year: 1974
price:        15.25
color: red

AppleScript[edit]

The method with AppleScript "records" is to concatenate them. The result is a third record containing the labels from both contributors, the values from the record to the left of the operator being kept where labels are shared. The bars with some of the labels below are to distinguish them as "user" labels from tokenised ones that are provided as standards for use by scriptable applications and scripting additions. However, merging records works with tokenised labels too.

set baseRecord to {|name|:"Rocket Skates", price:12.75, |color|:"yellow"}
set updateRecord to {price:15.25, |color|:"red", |year|:1974}
 
set mergedRecord to updateRecord & baseRecord
return mergedRecord
Output:
{price:15.25, |color|:"red", |year|:1974, |name|:"Rocket Skates"}

Arturo[edit]

details: #[name: "Rocket Skates" price: 12.75 colour: 'yellow]
newDetails: extend details #[price: 15.25 colour: 'red year: 1974]
 
print newDetails
Output:
[name:Rocket Skates price:15.25 colour:red year:1974]

AutoHotkey[edit]

merge(base, update){
Merged := {}
for k, v in base
Merged[k] := v
for k, v in update
Merged[k] := v
return Merged
}
Examples:
base := {"name":"Rocket Skates", "price":12.75, "color":"yellow"}
update := {"price":15.25, "color":"red", "year":1974}
Merged := merge(base, update)
for k, v in Merged
result .= k " : " v "`n"
MsgBox % result
Outputs:
color : red
name : Rocket Skates
price : 15.25
year : 1974

AWK[edit]

 
# syntax: GAWK -f ASSOCIATIVE_ARRAY_MERGING.AWK
#
# sorting:
# PROCINFO["sorted_in"] is used by GAWK
# 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])
}
}
 
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

B4X[edit]

Dim m1 As Map = CreateMap("name": "Rocket Skates", "price": 12.75, "color": "yellow")
Dim m2 As Map = CreateMap("price": 15.25, "color": "red", "year": 1974)
Dim merged As Map
merged.Initialize
For Each m As Map In Array(m1, m2)
For Each key As Object In m.Keys
merged.Put(key, m.Get(key))
Next
Next
Log(merged)

BaCon[edit]

DECLARE base$, update$, merge$ ASSOC STRING
 
base$("name") = "Rocket Skates"
base$("price") = "12.75"
base$("color") = "yellow"
 
PRINT "Base array"
FOR x$ IN OBTAIN$(base$)
PRINT x$, " : ", base$(x$)
NEXT
 
update$("price") = "15.25"
update$("color") = "red"
update$("year") = "1974"
 
PRINT NL$, "Update array"
FOR x$ IN OBTAIN$(update$)
PRINT x$, " : ", update$(x$)
NEXT
 
merge$() = base$()
merge$() = update$()
 
PRINT NL$, "Merged array"
FOR x$ IN OBTAIN$(merge$)
PRINT x$, " : ", merge$(x$)
NEXT
Output:
Base array
name : Rocket Skates
color : yellow
price : 12.75

Update array
year : 1974
color : red
price : 15.25

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

C++[edit]

#include <iostream>
#include <string>
#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;
}
Output:
key: color, value: red
key: name, value: Rocket Skates
key: price, value: 15.25
key: year, value: 1974

C#[edit]

using System;
using System.Collections.Generic;
using System.Linq;
 
public class Program
{
public static void Main() {
var baseData = new Dictionary<string, object> {
["name"] = "Rocket Skates",
["price"] = 12.75,
["color"] = "yellow"
};
var updateData = new Dictionary<string, object> {
["price"] = 15.25,
["color"] = "red",
["year"] = 1974
};
var mergedData = new Dictionary<string, object>();
foreach (var entry in baseData.Concat(updateData)) {
mergedData[entry.Key] = entry.Value;
}
foreach (var entry in mergedData) {
Console.WriteLine(entry);
}
}
}
Output:
[name, Rocket Skates]
[price, 15.25]
[color, red]
[year, 1974]

Clojure[edit]

 
(defn update-map [base update]
(merge base update))
 
(update-map {"name" "Rocket Skates"
"price" "12.75"
"color" "yellow"}
{"price" "15.25"
"color" "red"
"year" "1974"})
 
Output:
{"name" "Rocket Skates", "price" "15.25", "color" "red", "year" "1974"}

Crystal[edit]

base = {"name" => "Rocket Skates", "price" => 12.75, "color" => "yellow"}
update = { "price" => 15.25, "color" => "red", "year" => 1974 }
 
puts base.merge(update)
Output:
{"name" => "Rocket Skates", "price" => 15.25, "color" => "red", "year" => 1974}

Dart[edit]

 
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}');
 
 
}
 

Delphi[edit]

Translation of: C#
 
program Associative_arrayMerging;
 
{$APPTYPE CONSOLE}
 
uses
System.Generics.Collections;
 
type
TData = TDictionary<string, Variant>;
 
var
baseData, updateData, mergedData: TData;
entry: string;
 
begin
baseData := TData.Create();
baseData.Add('name', 'Rocket Skates');
baseData.Add('price', 12.75);
baseData.Add('color', 'yellow');
 
updateData := TData.Create();
updateData.Add('price', 15.25);
updateData.Add('color', 'red');
updateData.Add('year', 1974);
 
mergedData := TData.Create();
for entry in baseData.Keys do
mergedData.AddOrSetValue(entry, baseData[entry]);
 
for entry in updateData.Keys do
mergedData.AddOrSetValue(entry, updateData[entry]);
 
for entry in mergedData.Keys do
Writeln(entry, ' ', mergedData[entry]);
 
mergedData.Free;
updateData.Free;
baseData.Free;
 
Readln;
end.
 
 
Output:
price 15,25
year 1974
color red
name Rocket Skates

Elixir[edit]

Elixir has a built-in hashmap type, called Map.

base = %{name: "Rocket Skates", price: 12.75, color: "yellow"}
update = %{price: 15.25, color: "red", year: 1974}
result = Map.merge(base, update)
IO.inspect(result)
Output:
%{color: "red", name: "Rocket Skates", price: 15.25, year: 1974}

The above sample uses atoms as the key type. If strings are needed, the base map would look like this:

base = %{"name" => "Rocket Skates", "price" => 12.75, "color" => "yellow"}

F#[edit]

 
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
 
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[edit]

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
USING: assocs prettyprint ;
 
{ { "name" "Rocket Skates" } { "price" 12.75 } { "color" "yellow" } }
{ { "price" 15.25 } { "color" "red" } { "year" 1974 } }
assoc-union .
Output:
V{
    { "name" "Rocket Skates" }
    { "price" 15.25 }
    { "color" "red" }
    { "year" 1974 }
}

Go[edit]

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

Haskell[edit]

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:

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

Icon and Unicon[edit]

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

J[edit]

 
merge=: ,. NB. use: update merge original
compress=: #"1~ ~:@:keys
keys=: {.
values=: {:
get=: [: > ((i.~ keys)~ <)~ { [email protected]:] NB. key get (associative array)
pair=: [: |: <;._2;._2
 

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[edit]

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);
}
}
Output:
{name=Rocket Skates, color=red, year=1974, price=15.25}

JavaScript[edit]

(() => {
'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
))
})();
Output:
{
  "name": "Rocket Skates",
  "price": 15.25,
  "color": "red",
  "year": 1974
}

jq[edit]

Mapping “associative array” to “JSON object” in the natural way, the specified operation corresponds exactly to addition in jq, so that if A and B are the first and second objects respectively, then the jq expression `A + B` will yield the required result (as a JSON object).

Julia[edit]

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[edit]

 
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")
}
 
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[edit]

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

Mathematica / Wolfram Language[edit]

a1 = <|"name" -> "Rocket Skates", "price" -> 12.75, "color" -> "yellow"|>;
a2 = <|"price" -> 15.25, "color" -> "red", "year" -> 1974|>;
Merge[{a1, a2}, Last]
Output:
<|"name" -> "Rocket Skates", "price" -> 15.25, "color" -> "red", "year" -> 1974|>

MiniScript[edit]

MiniScript supports merging maps with the + operator.

base = {"name":"Rocket Skates", "price":12.75, "color":"yellow"}
update = {"price":15.25, "color":"red", "year":1974}
 
result = base + update
 
print result
Output:
{"color": "red", "name": "Rocket Skates", "price": 15.25, "year": 1974}

Nim[edit]

import tables
 
let t1 = {"name": "Rocket Skates", "price": "12.75", "color": "yellow"}.toTable
let t2 = {"price": "15.25", "color": "red", "year": "1974"}.toTable
 
var t3 = t1 # Makes a copy.
for key, value in t2.pairs:
t3[key] = value
 
echo t3
Output:
{"name": "Rocket Skates", "year": "1974", "color": "red", "price": "15.25"}

Objective-C[edit]

Works with: Cocoa
#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;
}
Output:
{
    color = red;
    name = "Rocket Skates";
    price = "15.25";
    year = 1974;
}

OCaml[edit]

Original version by User:Vanyamil

Note that, given OCaml's strong typing, we must declare a type here for the 3-type data. In general, would need the specific data type for the task, or use a PPX rewriter (effectively a compiler middleware) that can rewrite code based on dynamic type extensions.

Helper code for all 3 versions:

 
type ty =
| TFloat of float
| TInt of int
| TString of string
 
type key = string
type assoc = string * ty
 
let string_of_ty : ty -> string = function
| TFloat x -> string_of_float x
| TInt i -> string_of_int i
| TString s -> s
 
let print_pair key el =
Printf.printf "%s: %s\n" key (string_of_ty el)
;;
 

Association list : naive and functional approach.

 
let l1 : assoc list = [
("name", TString "Rocket Skates");
("price", TFloat 12.75);
("color", TString "yellow")
] ;;
 
let l2 : assoc list = [
("price", TFloat 15.25);
("color", TString "red");
("year", TInt 1974)
] ;;
 
let rec merge_assoc_list (base_list : assoc list) (add_list : assoc list) : assoc list =
List.fold_left
(fun l (key, val_) ->
(key, val_) :: (List.remove_assoc key l)
)
base_list
add_list
;;
 
let l' = merge_assoc_list l1 l2 ;;
 

Binary tree/Map functor : proper functional approach.

Works with: OCaml version above 4.03 for union function
 
module StringMap = Map.Make(String) ;;
 
let print_map = StringMap.iter print_pair ;;
 
let map_merge (base : ty StringMap.t) (add : ty StringMap.t) : ty StringMap.t =
StringMap.union (fun key v1 v2 -> Some v2) base add
;;
 
let m1 = StringMap.(
empty
|> add "name" (TString "Rocket Skates")
|> add "price" (TFloat 12.75)
|> add "color" (TString "yellow")
) ;;
 
let m2 = StringMap.(
empty
|> add "price" (TFloat 15.25)
|> add "color" (TString "red")
|> add "year" (TInt 1974)
) ;;
 
let m' = map_merge m1 m2 ;;
 
print_map m' ;;
 

Hash table : imperative/mutable approach.

 
(* Updates the base table with the bindings from add *)
let hash_merge (base : (string, ty) Hashtbl.t) (add : (string, ty) Hashtbl.t) : unit =
Hashtbl.iter (Hashtbl.replace base) add
 
let print_hashtbl t =
Hashtbl.iter print_pair t
 
let h1 : (string, ty) Hashtbl.t = Hashtbl.create 10 ;;
Hashtbl.add h1 "name" (TString "Rocket Skates") ;;
Hashtbl.add h1 "price" (TFloat 12.75) ;;
Hashtbl.add h1 "color" (TString "yellow") ;;
 
let h2 : (string, ty) Hashtbl.t = Hashtbl.create 10 ;;
Hashtbl.add h2 "price" (TFloat 15.25) ;;
Hashtbl.add h2 "color" (TString "red") ;;
Hashtbl.add h2 "year" (TInt 1974) ;;
 
hash_merge h1 h2 ;;
 
print_hashtbl h1 ;;
 

Ol[edit]

 
(define a1 {
'name "Rocket Skates"
'price 12.75
'color "yellow"
})
 
(define a2 {
'price 15.25
'color "red"
'year 1974
})
 
(print "a1: " a1)
(print "a2: " a2)
 
(define (collide a b) b) ; will use new key value
(print "merged a1 a2: " (ff-union a1 a2 collide))
 
Output:
a1: #ff((name . Rocket Skates) (price . 51/4) (color . yellow))
a2: #ff((price . 61/4) (color . red) (year . 1974))
merged a1 a2: #ff((name . Rocket Skates) (price . 61/4) (color . red) (year . 1974))

Perl[edit]

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;
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[edit]

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

Phixmonti[edit]

include ..\Utilitys.pmt
 
def scand /# dict key -- dict n #/
0 var flag
var ikey
len for
var i
i 1 2 tolist sget
ikey == if i var flag exitfor endif
endfor
flag
enddef
 
 
def getd /# dict key -- dict data #/
scand
dup if get 2 get nip else drop "Unfound" endif
enddef
 
 
def setd /# dict ( key data ) -- dict #/
1 get rot swap
scand
rot swap
dup if set else put endif
enddef
 
/# ---------- MAIN ---------- #/
 
( ( "name" "Rocket Skates" )
( "price" 12.75 )
( "color" "yellow" ) )
 
dup
 
( ( "price" 15.25 )
( "color" "red" )
( "year" 1974 ) )
 
len for
get rot swap setd swap
endfor
 
swap
 
pstack
 

PHP[edit]

<?
$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);
?>
Output:
Array
(
    [price] => 15.25
    [color] => red
    [year] => 1974
    [name] => Rocket Skates
)

Alternative:

<?
$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);
?>
Output:
Array
(
    [name] => Rocket Skates
    [price] => 15.25
    [color] => red
    [year] => 1974
)

PureBasic[edit]

NewMap m1.s()
NewMap m2.s()
NewMap m3.s()
 
m1("name")="Rocket Skates"
m1("price")="12.75"
m1("color")="yellow"
 
m2("price")="15.25"
m2("color")="red"
m2("year")="1974"
 
CopyMap(m1(),m3())
 
ForEach m2()
m3(MapKey(m2()))=m2()
Next
 
ForEach m3()
Debug MapKey(m3())+" : "+m3()
Next
Output:
price : 15.25
color : red
year : 1974
name : Rocket Skates

Python[edit]

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

Works with: Python version 3.5+
base = {"name":"Rocket Skates", "price":12.75, "color":"yellow"}
update = {"price":15.25, "color":"red", "year":1974}
 
result = {**base, **update}
 
print(result)
Output:
{'name': 'Rocket Skates', 'price': 15.25, 'color': 'red', 'year': 1974}
Alternative
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)
Output:
{'name': 'Rocket Skates', 'price': 15.25, 'color': 'red', 'year': 1974}
New alternative using '|'
Python 3.9.0 (tags/v3.9.0:9cf6752, Oct  5 2020, 15:34:40) [MSC v.1927 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license()" for more information.
>>> base = {"name":"Rocket Skates", "price":12.75, "color":"yellow"}
>>> update = {"price":15.25, "color":"red", "year":1974}
>>> result = base | update
>>> result
{'name': 'Rocket Skates', 'price': 15.25, 'color': 'red', 'year': 1974}
>>>

Racket[edit]

#lang racket/base
 
(require racket/hash)
 
(module+ test
(require rackunit)
 
(define base-data (hash "name" "Rocket Skates"
"price" 12.75
"color" "yellow"))
 
(define update-data (hash "price" 15.25
"color" "red"
"year" 1974))
 
(hash-union base-data update-data #:combine (λ (a b) b)))
 
Output:
'#hash(("color" . "red") ("name" . "Rocket Skates") ("price" . 15.25) ("year" . 1974))

Raku[edit]

(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.

# Show original hashes
say my %base = :name('Rocket Skates'), :price<12.75>, :color<yellow>;
say my %update = :price<15.25>, :color<red>, :year<1974>;
 
# Need to assign to anonymous hash to get the desired results and avoid mutating
# TIMTOWTDI
say "\nUpdate:\n", join "\n", sort %=%base, %update;
# Same
say "\nUpdate:\n", {%base, %update}.sort.join: "\n";
 
say "\nMerge:\n", join "\n", sort ((%=%base).push: %update)».join: ', ';
# Same
say "\nMerge:\n", ({%base}.push: %update)».join(', ').sort.join: "\n";
 
# Demonstrate unmutated hashes
say "\n", %base, "\n", %update;
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[edit]

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.

/*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
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

Ring[edit]

 
load "stdlib.ring"
 
list1 = [:name = "Rocket Skates", :price = 12.75, :color = "yellow"]
list2 = [:price = 15.25, :color = "red", :year = 1974]
 
for n = 1 to len(list2)
flag = 0
for m = 1 to len(list1)
if list2[n][1] = list1[m][1]
flag = 1
del(list1,m)
add(list1,[list2[n][1],list2[n][2]])
exit
ok
next
if flag = 0
add(list1,[list2[n][1],list2[n][2]])
ok
next
 
for n = 1 to len(list1)
see list1[n][1] + " = " + list1[n][2] + nl
next
 

Output:

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

Ruby[edit]

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

Rust[edit]

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

SenseTalk[edit]

In addition to setting individual property values, SenseTalk includes 5 built-in operations for modifying property lists, to: add properties, replace properties, remove properties, retain properties, and rename properties. The operation to replace properties is needed for this task.

set base to {name:"Rocket Skates", price:12.75, color:"yellow"}
 
set update to {price:15.25, color:"red", year:1974}
 
put "Base data: " & base
put "Update data: " & update
 
// replacing as an operator, to generate merged data on the fly:
put "Merged data: " & base replacing properties in update
 
// replace as a command, to modify base data in place:
replace properties of update in base
put "Base after update: " & base
 
Output:
Base data: {color:"yellow", name:"Rocket Skates", price:12.75}
Update data: {color:"red", price:15.25, year:1974}
Merged data: {color:"red", name:"Rocket Skates", price:15.25, year:1974}
Base after update: {color:"red", name:"Rocket Skates", price:15.25, year:1974}

Smalltalk[edit]

base := Dictionary withAssociations:{ 
'name'-> 'Rocket Skates' .
'price' -> 12.75 .
'color' -> 'yellow' }.
 
update := Dictionary withAssociations:{
'price' -> 15.25 .
'color' -> 'red' .
'year' -> 1974 }.
 
result := Dictionary new
declareAllFrom:base;
declareAllFrom:update.
 
Transcript showCR: result.
Output:
Dictionary(name->Rocket Skates price->15.25 year->1974 color->red)

Swift[edit]

Works with: Swift version 5+
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)
Output:
["price": 15.25, "name": "Rocket Skates", "color": "red", "year": 1974]

Tcl[edit]

set dict1 [dict create name "Rocket Skates" price 12.75 color yellow]
set dict2 [dict create price 15.25 color red year 1974]
dict for {key val} [dict merge $dict1 $dict2] {
puts "$key: $val"
}
Output:
name: Rocket Skates
price: 15.25
color: red
year: 1974

VBA[edit]

3 ways to do this tasks : First : With Arrays + Type

 
Private Type Associative
Key As String
Value As Variant
End Type
Sub Main_Array_Associative()
Dim BaseArray(2) As Associative, UpdateArray(2) As Associative
FillArrays BaseArray, UpdateArray
ReDim Result(UBound(BaseArray)) As Associative
MergeArray Result, BaseArray, UpdateArray
PrintOut Result
End Sub
Private Sub MergeArray(Res() As Associative, Base() As Associative, Update() As Associative)
Dim i As Long, Respons As Long
Res = Base
For i = LBound(Update) To UBound(Update)
If Exist(Respons, Base, Update(i).Key) Then
Res(Respons).Value = Update(i).Value
Else
ReDim Preserve Res(UBound(Res) + 1)
Res(UBound(Res)).Key = Update(i).Key
Res(UBound(Res)).Value = Update(i).Value
End If
Next
End Sub
Private Function Exist(R As Long, B() As Associative, K As String) As Boolean
Dim i As Long
Do
If B(i).Key = K Then
Exist = True
R = i
End If
i = i + 1
Loop While i <= UBound(B) And Not Exist
End Function
Private Sub FillArrays(B() As Associative, U() As Associative)
B(0).Key = "name"
B(0).Value = "Rocket Skates"
B(1).Key = "price"
B(1).Value = 12.75
B(2).Key = "color"
B(2).Value = "yellow"
U(0).Key = "price"
U(0).Value = 15.25
U(1).Key = "color"
U(1).Value = "red"
U(2).Key = "year"
U(2).Value = 1974
End Sub
Private Sub PrintOut(A() As Associative)
Dim i As Long
Debug.Print "Key", "Value"
For i = LBound(A) To UBound(A)
Debug.Print A(i).Key, A(i).Value
Next i
Debug.Print "-----------------------------"
End Sub

Second way (simply) : with the Scripting Dictionary Object :

Sub Main_With_Dictionary()
Dim Base As Object, Update As Object, Merged As Object, K As Variant
'INIT VARIABLE
Set Base = CreateObject("Scripting.Dictionary")
Set Update = CreateObject("Scripting.Dictionary")
Set Merged = Base
'FILL Base & Update
Base.Add "name", "Rocket Skates"
Base.Add "price", 12.75
Base.Add "color", "yellow"
Update.Add "price", 15.25
Update.Add "color", "red"
Update.Add "year", 1974
'Fill Merge
For Each K In Update.Keys
Merged(K) = Update(K)
Next
'Print Out
Debug.Print "Key", "Value"
For Each K In Merged.Keys
Debug.Print K, Merged(K)
Next K
End Sub

And the Third : With a Class Module (named ClassArrayAssociative) The Class Module code:

Option Explicit
 
Private mKey As String
Private mValue As Variant
 
Public Property Get Value() As Variant
Value = mValue
End Property
Public Property Let Value(iValue As Variant)
mValue = iValue
End Property
Public Property Get Key() As Variant
Key = mKey
End Property
Private Property Let Key(iKey As Variant)
mKey = iKey
End Property
 
Public Sub Add(K As String, V As Variant)
Value = V
Key = K
End Sub

The Module code :

Sub Main_With_Class()
Dim Base(2) As New ClassArrayAssociative, Up(2) As New ClassArrayAssociative
ReDim Result(UBound(Base)) As New ClassArrayAssociative
'FILL Base & Update
Base(0).Add "name", "Rocket Skates"
Base(1).Add "price", 12.75
Base(2).Add "color", "yellow"
Result = Base
Up(0).Add "price", 15.25
Up(1).Add "color", "red"
Up(2).Add "year", 1974
'Update Result with Up
Update Result, Up
'Print Out
Print_Out_2 Result
End Sub
Private Sub Update(R() As ClassArrayAssociative, U() As ClassArrayAssociative)
Dim i As Long, j As Long, Flag As Boolean
For i = LBound(U) To UBound(U)
j = LBound(R)
Flag = False
Do While j <= UBound(R) And Not Flag
If R(j).Key = U(i).Key Then
R(j).Value = U(i).Value
Flag = True
End If
j = j + 1
Loop
If Not Flag Then
ReDim Preserve R(UBound(R) + 1)
Set R(UBound(R)) = New ClassArrayAssociative
R(UBound(R)).Add U(i).Key, U(i).Value
End If
Next i
End Sub
Private Sub Print_Out_2(A() As ClassArrayAssociative)
Dim i As Long
Debug.Print "Key", "Value"
For i = LBound(A) To UBound(A)
Debug.Print A(i).Key, A(i).Value
Next i
Debug.Print "-----------------------------"
End Sub
Output:
Key           Value
name          Rocket Skates
price          15,25 
color         red
year           1974 
-----------------------------


Wren[edit]

var mergeMaps = Fn.new { |m1, m2|
var m3 = {}
for (key in m1.keys) m3[key] = m1[key]
for (key in m2.keys) m3[key] = m2[key]
return m3
}
 
var base = { "name": "Rocket Skates" , "price": 12.75, "color": "yellow" }
var update = { "price": 15.25, "color": "red", "year": 1974 }
var merged = mergeMaps.call(base, update)
System.print(merged)
Output:
{name: Rocket Skates, color: red, price: 15.25, year: 1974}

zkl[edit]

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)) });
Output:
price	15.25
color	red
year	1974
name	Rocket Skates