How to Create A Map From Two Arrays In Elixir?

To create a map from two arrays in Elixir, you can use the Enum.zip/2 function to combine the two arrays into a list of tuples, and then use the Map.new/1 function to convert the list of tuples into a map. Here's an example code snippet:

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array1 = [:key1, :key2, :key3]
array2 = [1, 2, 3]

zipped = Enum.zip(array1, array2)
map = Map.new(zipped)

IO.inspect(map)

In this example, array1 and array2 are the two arrays that we want to combine into a map. We use Enum.zip(array1, array2) to create a list of tuples where each tuple contains an element from array1 and array2. Then, we use Map.new(zipped) to convert the list of tuples into a map.

The resulting map will look like this:

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%{:key1 => 1, :key2 => 2, :key3 => 3}

What is the syntax for creating an empty map in Elixir?

The syntax for creating an empty map in Elixir is as follows:

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%{}

This creates an empty map with no key-value pairs.

How to merge two maps in Elixir?

To merge two maps in Elixir, you can use the Map.merge/2 function. Here is an example of how to merge two maps:

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map1 = %{a: 1, b: 2}
map2 = %{b: 3, c: 4}

merged_map = Map.merge(map1, map2)

IO.inspect(merged_map)

This will output:

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%{a: 1, b: 3, c: 4}

The Map.merge/2 function combines the key-value pairs of two maps. If there are duplicate keys, the value from the second map will overwrite the value from the first map.

How to pattern match on maps with guard clauses in Elixir?

To pattern match on maps with guard clauses in Elixir, you can use the | operator in the map pattern to match on specific key-value pairs in the map, and then use guard clauses to add additional conditions. Here's an example of how to pattern match on a map with guard clauses:

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defmodule Example do
  def example_function(%{foo: value} = map) when is_integer(value) do
    IO.puts "Value of foo is an integer: #{value}"
  end

  def example_function(%{bar: value} = map) when is_list(value) do
    IO.puts "Value of bar is a list: #{value}"
  end

  def example_function(_map) do
    IO.puts "Map does not match any pattern"
  end
end

map1 = %{foo: 123}
map2 = %{bar: [1, 2, 3]}
map3 = %{baz: "hello"}

Example.example_function(map1) # Output: Value of foo is an integer: 123
Example.example_function(map2) # Output: Value of bar is a list: [1, 2, 3]
Example.example_function(map3) # Output: Map does not match any pattern

In the example above, the example_function function takes a map as an argument and pattern matches on specific key-value pairs in the map using guard clauses to check the value type. If the map matches the pattern with a guard clause, the corresponding message is printed. If the map does not match any pattern, a default message is printed.

How to access values from a map in Elixir?

In Elixir, you can access values from a map using the Map.get/2 function or pattern matching.

Using Map.get/2 function:

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map = %{"key1" => "value1", "key2" => "value2", "key3" => "value3"}

value = Map.get(map, "key1")
IO.puts(value) # Output: value1

value = Map.get(map, "key4", "default")
IO.puts(value) # Output: default

Using pattern matching:

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%{key1: value} = %{:key1 => "value1", :key2 => "value2", :key3 => "value3"}
IO.puts(value) # Output: value1

If the key does not exist in the map, Map.get/2 will return nil. You can provide a default value as the second argument to be returned instead of nil.