• https://dev.to/turbaszek/flat-map-in-python-3g98

TL;DR

double list comprehension with 10_000 * 10 class objects => 4.5945 ms

flat_map = lambda f, xs: [y for ys in xs for y in f(ys)]

ls = [[1, 2, 3], [4, 5, 6]]
flat_map(lambda ys: ys, ls)

ls = ['a,b,c', 'd,e,f', 'g,h,i', 'j,k,l']
flat_map(lambda ys: ys.split(','), ls)

for and extend with 10_000 * 10 class objects => 2.7347ms

def flat_map(f, xs):
    ys = []
    for x in xs:
        ys.extend(f(x))
    return ys

2023-08-15 추가: 2차원 리스트를 1차원 리스트로

[x for sublist in wholelist for x in sublist],