sorting strings numerically while dealing with missing values

Wed Dec 28 15:43:41 EST 2016

On Wed, Dec 28, 2016 at 2:14 PM, Larry Martell <larry.martell at gmail.com> wrote:
>> I have a list containing a list of strings that I want to sort
> numerically by one of the fields. I am doing this:
>> sorted(rows, key=float(itemgetter(sortby)))

I'm guessing that you left out a lambda here since the key argument
takes a function.
> Which works fine as long as all the sort keys convert to a float.
> Problem is that some are blank or None and those throw an exception.
> How can I handle that case and still sort? I'd want the blank or None
> fields to come out either at the beginning or end of the sorted list
> (not sure what the customer wants for this yet).

def sort_key(sortby, none_first=False):
 def key(row):
 try:
 value = float(row[sortby])
 except ValueError:
 value = None
 return ((value is None) != none_first, value)
 return key
sorted(rows, key=sort_key(4, none_first=True))