how this special python list generated? -

i faced question confused me lot. meant generate list , reason did like:

mylist = [i in range(5), j j in range(5)] 

then interpreter complained me that invalid syntax @ position 'j' right before 'for'. define j before list. explain me why did not need define 'i' 'j' ?

i expected like:

[[0,1,2,3,4],[0,1,2,3,4]] 

however, got (i assign 2 j in advance)

[[0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4], 2, 2, 2, 2, 2] 

i confused here, tell me why got outcome?

thanks lot in advance.

what trying create two nested lists, nest comprehensions:

[[i in range(5)], [j j in range(5)]] 

or, since not doing anything expression, just:

[list(range(5)), list(range(5))] 

in python 2, list() call redundant.

you did not share 'define j outside list comprehension code' looked like, realize list comprehension supports nested loops.

a list comprehension can seen series of loops , if statements, which, read left right seen nested statements:

[i in range(5) j in range(5)] 

should read as:

for in range(5):     j in range(5):         outputlist.append(i) 

judging output did instead:

[j in range(5)] 

where j set range(5) on python 2.