Question about listdir/regex/sort

[quailman]

Hi all. I'm kind of a python noobie, this is for my first usefull program, beyond just playing around with the language. Any help is appreciated. Here's the code that throws an error.

import re, os
 
files = os.listdir(os.getcwd())
#files = ['blue13', 'red011', 'yellow1', 'green1000']
 
def getnum(filename): return float(re.findall(r'\d+',filename)[0])
def numsort(a,b): return cmp(getnum(a),getnum(b))
 
files.sort(numsort)
print files

this throws me

IndexError: list index out of range

if I switch the "files = " line for the commented one, everything works as it should

I've been banging my head on the keyboard for a couple hours now. It may be simple but I just don't see what's wrong.

Anyway... thanks for the help.

[bvdet]

Hi all. I'm kind of a python noobie, this is for my first usefull program, beyond just playing around with the language. Any help is appreciated. Here's the code that throws an error.

import re, os
 
files = os.listdir(os.getcwd())
#files = ['blue13', 'red011', 'yellow1', 'green1000']
 
def getnum(filename): return float(re.findall(r'\d+',filename)[0])
def numsort(a,b): return cmp(getnum(a),getnum(b))
 
files.sort(numsort)
print files

this throws me

IndexError: list index out of range

if I switch the "files = " line for the commented one, everything works as it should

I've been banging my head on the keyboard for a couple hours now. It may be simple but I just don't see what's wrong.

Anyway... thanks for the help.

You are encountering files that have no numbers in them. Example:

>>> getnum('split300.py')
300.0
>>> getnum('xmlscanner.py')
Traceback (most recent call last):
  File "<interactive input>", line 1, in ?
  File "C:\SDS2_7.0\macro\Work In Progress\re_files_with_numbers.py", line 7, in getnum
    return float(re.findall(r'\d+',filename)[0])
IndexError: list index out of range
>>> 

[bartonc]

Hi all. I'm kind of a python noobie, this is for my first usefull program, beyond just playing around with the language. Any help is appreciated. Here's the code that throws an error.

import re, os
 
files = os.listdir(os.getcwd())
#files = ['blue13', 'red011', 'yellow1', 'green1000']
 
def getnum(filename): return float(re.findall(r'\d+',filename)[0])
def numsort(a,b): return cmp(getnum(a),getnum(b))
 
files.sort(numsort)
print files

this throws me

IndexError: list index out of range

if I switch the "files = " line for the commented one, everything works as it should

I've been banging my head on the keyboard for a couple hours now. It may be simple but I just don't see what's wrong.

Anyway... thanks for the help.

And, just as a tip: Python allows the style of function def that you have use, but please don't do it. You will like yourself, and your program much better in the long run (because you will be able to read it more easily) if you stick with indents:

import re, os
 
files = os.listdir(os.getcwd())
#files = ['blue13', 'red011', 'yellow1', 'green1000']
 
def getnum(filename):
    return float(re.findall(r'\d+',filename)[0])
def numsort(a,b):
    return cmp(getnum(a),getnum(b))
 
files.sort(numsort)
print files

For example, at first glance I couldn't see these functions.

[bvdet]

Try this:

def getnum(filename):
    m = re.search(r'\d+',filename)
    if m: return int(m.group(0))
    return None

[quailman]

Wow! thanks you guys for the quick response. That took care of it, it's up and running like it should.

Just for reference, here's what it looks like now.

import re,os
 
files = os.listdir(os.getcwd())
#files = ['blue13', 'red011', 'yellow', 'green1000']
 
def numsort(c,d):
        def getnum(filename):
                m = re.search(r'\d+',filename)
                if m: return float(m.group(0))
                return None
        return cmp(getnum(c),getnum(d))
 
files.sort(numsort)
print files

Thanks again! I'll likely be back!