util.jl

"""
     column_vectors(A)

Given a two dimensional array `A` of size `m` x `n`, return an array
of `n` vectors being the columns in `A`. Each vector is of length `m`.

"""
function column_vectors(A)
    m,n = size(A)
    [A[:,i] for i in 1:n]
end


function row_vectors(A)
    m,n = size(A)
    [A[i,:] for i in 1:m]
end

"""
    skipnan(itr)

Return a copy of itr with NaNs removed.
"""
skipnan(itr) = filter(!isnan, itr)

"""
    findintervals(A, n=5)

Given a sorted array `A`, find the pairs of indices that split `A`
into intervals of size `n`.

"""
function findintervals(A, n=5)
    a = findfirst.(A .>= x for x in n:n:A[end])
    zip([1;a[1:end-1].+1], a)
end

"""
    mapintervals(f, A, intervals)

Maps a function `f` over `intervals` in `A`.
"""
function mapintervals(f, A, intervals)
    [f(a[x:y]) for (x,y) in intervals]
end

## contains is replaced by occursin