Basically I would like to be able to tell when I'm on the Nth item in a loop iteration. Any thoughts?
d = {1:2, 3:4, 5:6, 7:8, 9:0}
for x in d:
if last item: # <-- this line is psuedo code
print "last item :", x
else:
print x
Use enumerate:
#!/usr/bin/env python
d = {1:2, 3:4, 5:6, 7:8, 9:0}
# If you want an ordered dictionary (and have python 2.7/3.2),
# uncomment the next lines:
# from collections import OrderedDict
# d = OrderedDict(sorted(d.items(), key=lambda t: t[0]))
last = len(d) - 1
for i, x in enumerate(d):
if i == last:
print i, x, 'last'
else:
print i, x
# Output:
# 0 1
# 1 3
# 2 9
# 3 5
# 4 7 last
How about using enumerate?
>>> d = {1:2, 3:4, 5:6, 7:8, 9:0}
>>> for i, v in enumerate(d):
... print i, v # i is the index
...
0 1
1 3
2 9
3 5
4 7
for x in d.keys()[:-1]:
print x
if d: print "last item:", d.keys()[-1]
for x in d[:-1]: gives a TypeError: unhashable type when d = {1:2, 3:4, 5:6, 7:8, 9:0} because dictionary d's values are integers.
Commented
Jan 20, 2011 at 18:49
for x in d.keys()[:-1] here instead. @Apalala is iterating over the keys in d, not d itself. The fact that d's values are integers is irrelevant here.
.keys() for a few minutes. @martineau must have seen that one.
for x in d[:-1]: because I cut & pasted the whole code block as well as the OP's definition of d into a local .py file to generate the exact text of the error message for insertion into my comment. All I can do is take what I wrote back and say "sorry" since it sure appears that I was mistaken...
Commented
Jan 20, 2011 at 21:37
d = {1:2, 3:4, 5:6, 7:8, 9:0}
for i,x in enumerate(d):
print "last item :"+repr(x) if i+1==len(d) else x
But the last item of an unordered dictionary doesn't mean anything
list = [1,2,3]
last = list[-1]
for i in list:
if i == last:
print("Last:")
print i
Output:
1
2
Last:
3
Warning: Only works when the last two elements are not equal
for x in d:to iterate over the keys, but those keys are not always sorted in useful ways.