Map and broadcast

Map

map(f, c...) applies function f to each element of collection c that enter as the the second argument of the map function.

Below two lines of codes produce same output. This means that map also acts as a for loop.

map(x->x+2, 1:10)
[ x + 2 for x=1:10]

Output:

10-element Vector{Int64}:
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12

The function that enters the first argument of map could take multiple arguments; it could be more than one argument. Notice in the below example that we have two arguments for the anonymous function (x,y)->x-2*y+2. Then the second argument of map should indicate the collection of possible values of x, while the third argument of map indicates those of y. The anonymous function is applied element wise.

map((x,y)->x-y + 2, 1:10, -10:-1)

10-element Vector{Int64}:
 13
 13
 13
 13
 13
 13
 13
 13
 13
 13

Broadcasting

broadcast, which expands singleton dimensions in array arguments to match the corresponding dimension in the other array without using extra memory, and applies the given function elementwise.
Source: https://docs.julialang.org/en/v1/manual/arrays/#Broadcasting

a=[1,2]
b=[1 2 ; 3 4]
broadcast(+, a, b)

Output:

a 
2-element Vector{Int64}:
 1
 2

b
2×2 Matrix{Int64}:
 1  2
 3  4

broadcast(+, a, b)
2×2 Matrix{Int64}:
 2  3
 5  6

Punctuation

Reference

https://docs.julialang.org/en/v1/base/collections/#Base.map https://docs.julialang.org/en/v1/manual/arrays/#Broadcasting https://docs.julialang.org/en/v1/base/punctuation/