in place list modification necessary? What's a better idiom?

[MRAB]

Carl Banks wrote:
> MooMaster wrote:
>> So I'm reading in values from a file, and for each column I need to
>> dynamically discover the range of possible values it can take and
>> quantize if necessary. This is the solution I've come up with:
>>
[snip]
>> #harvested from http://www.rosettacode.org/wiki/IsNumeric#Python
>> def isNumeric(string):
>>     try:
>>         i = float(string)
>>     except ValueError:
>>         return False
>>     return True
> 
[snip]
> 
> import collections
> import itertools
> 
> def createInitialCluster(fileName):
>     fixedPoints = []
>     # quantization is a dict that assigns sequentially-increasing
> numbers
>     # to values when reading keys that don't yet exit
>     quantization = defaultdict.collections(itertools.count().next)
>     with open(fileName, 'r') as f:
>         for line in f:
>             dimensions = []
>             for s in line.rstrip('\n').split(","):
>                 if isNumeric(s):
>                     dimensions.append(float(s))
>                 else:
>                     dimensions.append(float(quantization[s]))
>             fixedPoints.append(Point(dimensions))
>     return Cluster(fixedPoints)
> 
I'd also remove the isNumeric() function. You're just converting to a
float if you can successfully convert to a float!

                 try:
                     dimensions.append(float(s))
                 except ValueError:
                     dimensions.append(float(quantization[s]))