Question

Hi! Fellow OCW students! I am trying to solve problem 3 on the problem set 3. I keep getting error messages. I don't see why. Could you guys pick that out?

http://pastebin.com/5DfgyJ3M

Thanks!

Answer 1

What's the error messages?

Answer 2

MatchPair is declared as a tuple. Tuples are immutable ( can't be changed ). A list would work better.

Answer 3

whats the error?

Answer 4

Hi! guys. The error message is following:

Traceback (most recent call last):
File "<pyshell#48>", line 1, in <module>
subStringMatchOneSub("abcabcabcabcd","bc")
File "/Users/piljoomoon/Documents/HW3.py", line 108, in subStringMatchOneSub
filtered = constrainedMatchPair(match1,match2,len(key1))
File "/Users/piljoomoon/Documents/HW3.py", line 44, in constrainedMatchPair
for second in range(0,len(secondMatch)):
TypeError: object of type 'NoneType' has no len()

Thank you for your help!

Answer 5

Sounds like secondMatch is either not declared, or it REALLY isn't what you think it is, so whatever is setting it's value isn't working properly.

Answer 6

hm..I am sure that secondMatch is a list. In what situation do you get this error? can you guys give me an example? : TypeError: object of type 'NoneType' has no len()

Answer 7

The easy way to prove it is to print secondMatch in line 43 of constrainedMatchPair. If that errors, guess what. If it doesn't, study what's printed to make sure that it's list syntax.

IMO, during debugging, when in doubt, print it out.

Answer 8

Thanks guys for the help!