[stillinbeta]

In most circumstances for (key, val) in data won't work, as the default dictionary iterable only contains the keys. You want for key, val in data.items():

[pcote]

I use dictionary comprehensions personally but I have mixed feelings about the syntax. It looks too much like set comprehensions on first glance. Compare the following to see what I mean.

myset = {x for x in "This is my stuff".split()}

mydict = {x:len(x) for x in "This is my stuff".split()}

[andreasvc]

Well I see what you mean but then again a comma looks very much like a period ...

The advantage of this syntax is that : unambiguously introduces a key: value pair, whereas (key, value) could also occur in a list comprehension (e.g., by accident).

[js2]

Or iteritems() for an iterable.

[andreasvc]

Erm, you can leave out 'in most circumstances' and 'default'; this the way they always work.

[andylei]

well,

    (key, val) in data 

works if

    data = {(1,2) : 3}

[andreasvc]

Well but then the variable names are just wrong.