Running multiple loops in Python

Question

Say I have two lists:

>>> passwordList = ['lee', 'venter', 'rusty']
>>> wrong_num = [5, 5, 0]

I loop the two lists together to combine the two list's corresponding indexes using:

>>>for p, w in zip(passwordList,wrong_num):
>>>      newFile.write("The password " + p + " was wrong by " + str(w) + "characters")

The result looks like this:

>>> The password lee was wrong by 5 characters
>>> The password venter was wrong by 5 characters
>>> The password rusty was wrong by 0 characters

My problem comes when I want to include a index variable to make the result look like:

>>>"The password entry 1: lee, was wrong by 5 characters"
>>>"The password entry 2: lee, was wrong by 5 characters"
>>>"The password entry 3: lee, was wrong by 5 characters

I want to index the first list so I can display 1, 2 and 3 for every item in the list. So for this I include another loop that makes the code look like this:

>>>for ind, item in enumerate(passwordList):
>>>        for p, w in zip(passwordList,wrong_num):
>>>             newFile.write("The password entry " + str(ind) + ": " + p + "is wrong by " + str(w) + " characters")

The result in the file newFile looks like this:

>>> Incorrect password 1: lee, wrong by 5 characters
>>> Incorrect password 1: lee, wrong by 5 characters
>>> Incorrect password 1: lee, wrong by 0 characters
>>> Incorrect password 2: venter, wrong by 5 characters
>>> Incorrect password 2: venter, wrong by 5 characters
>>> Incorrect password 2: venter, wrong by 0 characters
>>> Incorrect password 3: rusty, wrong by 5 characters
>>> Incorrect password 3: rusty, wrong by 5 characters
>>> Incorrect password 3: rusty, wrong by 0 characters

How can I stop this from happening and rather only print:

>>> Incorrect password 1 : lee, wrong by 5 characters
>>> Incorrect password 2 : venter, wrong by 5 characters
>>> Incorrect password 3: rusty, wrong by 0 characters

This is just for the theory, so please ignore that "rusty is wrong by 0 characters" still says incorrect password at the beginning of the sting.

Tim · Accepted Answer · 2015-09-02 10:59:11Z

4

Enumerate the result of zip() instead, leaving only one for loop:

>>> passwordList = ['lee', 'venter', 'rusty']
>>> wrong_num = [5, 5, 0]
>>> for i, (p, w) in enumerate(zip(passwordList,wrong_num)):
...   print "The password entry " + str(i) + ": " + p + "is wrong by " + str(w) + " characters"
...
The password entry 0: leeis wrong by 5 characters
The password entry 1: venteris wrong by 5 characters
The password entry 2: rustyis wrong by 0 characters

Another option is to make use of itertools

>>> from itertools import izip, count
>>> passwordList = ['lee', 'venter', 'rusty']
>>> wrong_num = [5, 5, 0]
>>> for i, p, w in izip(count(), passwordList, wrong_num):
...   print "The password entry " + str(i) + ": " + p + "is wrong by " + str(w) + " characters"
...
The password entry 0: leeis wrong by 5 characters
The password entry 1: venteris wrong by 5 characters
The password entry 2: rustyis wrong by 0 characters

If you need the indexes as 1 2 3 instead of 0 1 2 you can replace str(i) with str(i+1)

edited Sep 2, 2015 at 10:59

answered Sep 2, 2015 at 10:48

Tim

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3 Comments

Lee Venter Over a year ago

Thank you very much Tim, it was exactly what I needed! But one question please: Why when I try the bottom intertools, an error says: no module named intertools?

Tim Over a year ago

It's itertools, not intertools

Lee Venter Over a year ago

Ag, please excuse Tim, misread. Thanks again, I appreciate your help

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