You are using Python 3; use dict.items()
instead.
The Python 2 dict.iter*
methods have been renamed in Python 3, where dict.items()
returns a dictionary view instead of a list by default now. Dictionary views act as iterables in the same way dict.iteritems()
do in Python 2.
From the Python 3 What's New documentation:
dict
methods dict.keys()
, dict.items()
and dict.values()
return “views” instead of lists. For example, this no longer works: k = d.keys(); k.sort()
. Use k = sorted(d)
instead (this works in Python 2.5 too and is just as efficient).
- Also, the
dict.iterkeys()
, dict.iteritems()
and dict.itervalues()
methods are no longer supported.
Also, the .next()
method has been renamed to .__next__()
, but dictionary views are not iterators. The line graph.iteritems().next()
would have to be translated instead, to:
current = next(iter(graph.items()))
which uses iter()
to turn the items view into an iterable and next()
to get the next value from that iterable.
You'll also have to rename the next
variable in the while
loop; using that replaces the built-in next()
function which you need here. Use next_
instead.
The next problem is that you are trying to use current
as a key in cycles
, but current
is a tuple of an integer and a list of integers, making the whole value not hashable. I think you wanted to get just the next key instead, in which case next(iter(dict))
would give you that:
while graph:
current = next(iter(graph))
cycle = [current]
cycles[current] = cycle
while current in graph:
next_ = graph[current][0]
del graph[current][0]
if len(graph[current]) == 0:
del graph[current]
current = next_
cycle.append(next_)
This then produces some output:
>>> cycles
{0: [0, 3, 2, 1, 0], 2: [2, 6, 5, 4, 2], 6: [6, 8, 7, 9, 6]}
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