Question

Is there a way to efficiently iterate over the values/items in a dictionary that works in both Python 2 and Python 3?

In Python 2, I can write

for x in mydict:
for x in mydict.iterkeys():
for x in mydict.viewkeys():
for x in mydict.itervalues():
for x in mydict.viewvalues():
for x in mydict.iteritems():
for x in mydict.viewitems():

and in Python 3, I have the following possibilities:

for x in mydict:
for x in mydict.keys():
for x in mydict.values():
for x in mydict.items():

So, I can iterate over the keys with for x in mydict, and that works in both Python 2 and 3. But is there a way to iterate over values and key-value pairs (‘items’) that works universally? I need it for writing Python code that can be run in both Python versions.

(On a side note, other obstacles with iterators can be bypassed easily; take for example:

if sys.version_info.major<3:
    from itertools import izip as zip, imap as map

However, the dictionary methods cannot be redefined easily like map and zip.)

Any ideas?

Answer 1

values() version of Just another dunce’s answer

for value in (mydict[key] for key in mydict):

or

def dict_values(d):
   return (mydict[key] for key in mydict)

def dict_items(d):
   return ((key, mydict[key]) for key in mydict)

for value in dict_values(mydict):
    ...

for value in dict_items(mydict):
    ...

This is pretty crappy though. You could check the python version and instead of returning the generator, return d.items() or d.iteritems() as appropriate

I think a better question may be how to write Python2 code that works well with 2to3 and generates good Python3 code