Associative array/Merging

Associative array/Merging is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

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

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]

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}

Python

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

zkl

<lang zkl></lang> <lang zkl></lang>

Output: