Creating a list of functions in python (python function closure bug?)

Question

I understand functional programming well. I want to create a list of functions that each selects a different element of a list. I have reduced my problem to a simple example

Answer 1

You can do this using the itemgetter:

from operator import itemgetter
fun_list = []
for i in range(5):
    fun_list.append(itemgetter(i))

mylist = range(10)
print([f(mylist) for f in fun_list])

In your case, you are assigning a function to all elements referencing a global i with the value of i at the time of the call, which is 4 for all calls. You need some sort of currying.

Same without the itemgetter:

def indexer(i): return lambda y: y[i]

fun_list = []
for i in range(5):
    fun_list.append(indexer(i))

mylist = range(10)
print([f(mylist) for f in fun_list])