How to generate several functions using a for loop in Python? [duplicate]

Question

I am trying to generate several functions with different parameter i (see below) using a for loop, but it seems that all these functions are using the last item of i's. Could anyone tell me how to handle this?

This is a simplified example. I actually need to generate more than 200 functions with different parameters.

funs = ()
for i in range(2):
    f = lambda x: x+i
    funs += (f,)

Then it turns out that the two functions do the same thing:

funs[0](1)

Output: 2

funs[1](1)

Output: 2

But I expect the first function to give a result of 1 rather than 2.

Thank you very much in advance.

Answer 1

you have to break the dynamic binding to i, for instance by wrapping 2 lambdas together:

f = (lambda p : lambda x: x+p)(i)

that way, the value of i is captured, and functions hold a copy of i

Aside: I wouldn't use tuple to create the list for performance reasons when appending to funs (funs = () => funs = [])