Can I sort text by its numeric value in Python?

Question

I have dict in Python with keys of the following form:

mydict = {\'0\'     : 10,
          \'1\'     : 23,
          \'2.0\'   : 321,
          \'2.1\'   : 3         


        

Answer 1

Python's sorting functions can take a custom compare function, so you just need to define a function that compares keys the way you like:

def version_cmp(a, b):
  '''These keys just look like version numbers to me....'''
  ai = map(int, a.split('.'))
  bi = map(int, b.split('.'))
  return cmp(ai, bi)

for k in sorted(mydict.keys(), version_cmp):
  print k, mydict[k]

In this case you should better to use the key parameter to sorted(), though. See Ian Clelland's answer for an example for that.