Weird Lambda Behaviour In List Comprehension

I'm playing with lambda functions inside of list comprehension, and found some weird behaviour x = [(lambda x: i) for i in range(3)] print(x[0](0)) #print 2 instead of 0 print(x[1

Solution 1:

lambdas bind variables themselves, not the values that they had. i is changed to 2 at the end of the list comprehension, so all the lambdas refer to i at that point, and thus refer to 2.

To avoid this, you can use the default argument trick:

[lambda x,i=i:i for i inrange(3)]

This binds the value of i in the default argument (which is evaluated at function definition time).