Question

So I have a minor issue with a script I’m writing. I have a text file that looks something like:

'20 zebra 12 bear'

That’s just an example, the format is 1 line all items separated by spaces. The script works to sort them out and do a couple of other things to the strings but what I can’t figure out is how to keep it set the way it is. For example the above line should sort like this:

12
bear
20
zebra

I need to keep a number in the number place and a string in a strings place but they should be sorted alphanumerically.
Here is my script so far:

#!/usr/bin/python

# Make sure you use the proper modules.
import sys, string

# This area defines the arguments and returns a usage message should it be used incorrectly.
try:
  infilename = sys.argv[1]; outfilename = sys.argv[2]
except:
  print "Usage:",sys.argv[0], "infile outfile"; sys.exit(1)

ifile = open(infilename, 'r') # Opens the input file for reading
ofile = open(outfilename, 'w') # Opens the output file for writing
data = ifile.readlines()[0].split() # Reads the lines on the input file

# The items in the list are sorted here and defined by a space.
sort = sorted(data, key=lambda item: (int(item.partition(' ')[0])
                                   if item[0].isdigit() else float('inf'), item))

# Use this to remove any special characters in the list
filtered = [s.translate(None, string.punctuation) for s in sort]


ofile.write('\n'.join(filtered)) # Writes the final output to file (one on each line)



ifile.close() # Closes the input file
ofile.close() # Closes the output file

I know it’s not the prettiest but I haven’t been using Python long so if you have suggestions on how to make it prettier, I’m all ears. All I really need is to keep a number a number and a string a string but swap them around to sort. Thanks for any assistance given.

Answer 1

This is a really weird question.

def strange_sort(seq):
    """
    Sorts digitstrings (by integer value) and non-digitstrings in a
    sequence among themselves, preserving the original ds/non-ds
    signature.
    """
    numbers = iter(sorted((elem for elem in seq if elem.isdigit()), key=int))
    words = iter(sorted(elem for elem in seq if not elem.isdigit()))
    final = [next(numbers if elem.isdigit() else words) for elem in seq]
    return final

which gives

>>> strange_sort("1 2 3".split())
['1', '2', '3']
>>> strange_sort("1 2 10 3".split())
['1', '2', '3', '10']
>>> strange_sort("1 2 10 3 bear".split())
['1', '2', '3', '10', 'bear']
>>> strange_sort("2 1 bear 10 3".split())
['1', '2', 'bear', '3', '10']
>>> strange_sort("2 1 zebra 10 3 bear".split())
['1', '2', 'bear', '3', '10', 'zebra']
>>> strange_sort("20 zebra 12 bear".split())
['12', 'bear', '20', 'zebra']
>>> strange_sort("20 zebra 12 bear 3".split())
['3', 'bear', '12', 'zebra', '20']

Actually, this is basically @przemo_li’s suggestion worked out.

[edited to keep everything a string]