Something wrong in the body of the function

Question

I have a function that have to return True if and only if all the ints in L1 are the lengths of the strings in L2 at the corresponding positions. and the Precondition: len(L1) == len(L2).

EXAMPLE:

>>> are_lengths_of_strs([4, 0, 2], ['abcd', '', 'ef']) 
True

Below is the function:

def are_lengths_of_strs(L1, L2):
 result = True
 for i in range(len(L1)):
 if i in len(L1) != len(L2):
 result = False
 return result

It result in a error. The line if i in len(L1) != len(L2): is the wrong . Can someone help me in this line ??

Obs : I have to use !=

• sehe: "Something rotten in the state of Danmark"
• Lev Levitsky: +1 to sehe's comment, please use descriptive titles for your questions.

Answer 1

Corrected version of your code:

def are_lengths_of_strs(L1, L2):
 result = True
 for i in range(len(L1)):
 if L1[i] != len(L2[i]):
 result = False
 return result

Note that this is not pythonic, because you don't in fact need an index here:

def are_lengths_of_strs(L1, L2):
 result = True
 for i, l in zip(L1, L2)
 if i != len(l):
 result = False
 return result

Even shorter:

def are_lengths_of_strs(L1, L2):
 return all(i == len(l)
 for i, l in zip(L1, L2))

Answer 2

Your if condition is probably the problem:

 if i in len(L1) != len(L2):

This checks if i in len(L1), but len(L1) is an integer, which can't "contain" another number.

You have to iterate over the elements of each list:

def are_lengths_of_strs(L1, L2):
 result = True
 for i in range(len(L1)):
 if L1[i] != len(L2[i]):
 result = False
 return result

Also, get rid of result. A simple return statement will work just fine:

def are_lengths_of_strs(L1, L2):
 for i in range(len(L1)):
 if L1[i] != len(L2[i]):
 return False
 return True

If you want to get even more Pythonic, use zip:

def are_lengths_of_strs(L1, L2):
 for a, b in zip(L1, L2)
 if a != len(b):
 return False
 return True

Answer 3

use the built-in all() along with zip():

In [5]: all(x==len(y) for x,y in zip([4, 0, 2], ['abcd', '', 'ef']))
Out[5]: True

or if != is compulsory use any():

In [7]: not any(x != len(y) for x,y in zip([4, 0, 2], ['abcd', '', 'ef']))
Out[7]: True

or improving your code:

def are_lengths_of_strs(L1, L2):
 for x,y in zip(L1,L2):
 if x!=len(y):
 return False
 return True
In [12]: are_lengths_of_strs([4, 0, 2], ['abcd', '', 'ef'])
Out[12]: True