[Tutor] more fun and games with padded numbers

[Terry Carroll]

On Thu, 11 Jan 2007, Christopher Spears wrote:

> Let's say I have a series of files that are named like
> so:
> 
> 0001.ext
> 0230.ext
> 0041.ext
> 0050.ext
> 
> How would I convert these from a padding of 4 to a
> padding of 1?  In other words, I want the files to be
> renamed as:
> 
> 1.ext
> 230.ext
> 41.ext
> 50.ext

That doesn't look to me like a padding of 1; that looks to me like no 
padding.

But if that's what you want, I'm sure there's a better way, but my initial 
approach would be:

>>> oldnames = ["0001.ext", "0230.ext", "0041.ext", "0050.ext"]
>>> for name in oldnames:
...  newfname, fext = name.split('.')
...  newname = "%s.%s" % (int(newfname), fext)
...  print newname
...
1.ext
230.ext
41.ext
50.ext
>>>

Note that this assumes that the filename portion is entirely numeric.  
This would break on, for example, a file named 00abc.ext.

Actually, what I don't like here is the conversion of string to int to 
string for no real purpose.

> At first I used strip(), which was a mistake because
> it removed all the zeroes.

That should work, with an argument:

>>> oldnames = ["0001.ext", "0230.ext", "0041.ext", "0050.ext"]
>>> newnames = [name.strip('0') for name in oldnames]
>>> newnames
['1.ext', '230.ext', '41.ext', '50.ext']