Best way to shuffle elements in a vector of vectors

[mohamed82008]

@gabrielgellner

Anyone see anything I could do to make it faster / cleaner?

Best way to shuffle elements in a vector of vectors

If vector-of-vectors is the structure you want then you can do this: julia> using Random julia> data = [collect(1:5) for i in 1:10]; julia> foreach(shuffle!, data) julia> data 10-element Array{Array{Int64,1},1}: [3, 2, 5, 1, 4] [1, 2, 4, 5, 3] [2, 3, 1, 5, 4] [2, 4, 5, 3, 1] [2, 3, 4, 5, 1] [3, 1, 4, 5, 2] [1, 4, 5, 3, 2] [5, 3, 1, 4, 2] [4, 5, 3, 2, 1] [3, 2, 4, 5, 1] If you’d prefer to have a matrix with shuffled rows or columns, you can use views: julia> data = [j for i = 1:10…

To make it for columns instead of rows in Stefan’s second example, just use [:,i]. Also, use $ before variables with @btime to get proper timings.

@gabrielgellner

Also is it the correct style to return nothing from an inplace operation?

Style question for functions with in place transforms and return types

It is perfectly reasonable to return a value from an in-place function; most in-place functions in Julia return something useful. You usually want to think about how your function f!(X) might be composed with other function in order to decide on the return value. For example, many in-place functions return the altered collection, so that you can compose them with other functions that act on collections, e.g. first(sort!(push!(A, x))) # returns first element of sorted [A; x] In other cases, e…