使用Enum遍历Elixir中的元组列表

Question

I am trying to iterate over a list of tuples through Enum.map .

coordinates = [{0,0},{1,0},{0,1}]
newcoordinates = Enum.map(coordinates,fn({X,Y})->{X+1,Y+1})

This code is not valid . How can I do this ?

Answer 1

First of all, you're missing an end after the function declaration. Second, in Elixir, identifiers starting with upper case are atoms and lower case are variables, unlike Erlang where upper case are variables and lower case are atoms. So you just need to make them lowercase:

iex(1)> coordinates = [{0, 0},{1, 0},{0, 1}]
[{0, 0}, {1, 0}, {0, 1}]
iex(2)> newcoordinates = Enum.map(coordinates, fn {x, y} -> {x + 1, y + 1} end)
[{1, 1}, {2, 1}, {1, 2}]

Answer 2

You can also use comprehensions :

for {x, y} <- [{0,0},{1,0},{0,1}], do: {x+1, y+1}

Comprehensions are syntactic sugar for enumeration, so it's equivalent to using Enum .