lambda - Vectorize Loop with nested lists in Python -

looking vectorizing loop in python:

for in range(len(listone)):          listtwo.append(listthree[listfour[a]]) 

i want test potential performance gains not having call append via loop. if not vectorization, perhaps lambda expression might suffice? thoughts or assistance immensely helpful! thank time!

there's nothing wrong loop, change comprehension if want avoid append():

listtwo = [listthree[listfour[a]] in range(len(listone))]