andrea.gavana wrote:
> If I simplify the problem, suppose I have 2 lists like:
>
> a = range(10)
> b = range(20,30)
>
> What I would like to have, is a "union" of the 2 list in a single tuple. In
> other words (Python words...):
>
> c = (0, 20, 1, 21, 2, 22, 3, 23, 4, 24, 5, 25, .....
The 'yield' statement is very useful for this sort of thing as
well as the itertools module. I thought the latter had something
for this already but I don't see it. Here's an implementation
>>> import itertools
>>> def round_robin(*iterables):
... iterables = map(iter, iterables)
... for element in itertools.cycle(iterables):
... yield element.next()
...
>>> tuple(round_robin(range(10), range(20, 30)))
(0, 20, 1, 21, 2, 22, 3, 23, 4, 24, 5, 25, 6, 26, 7, 27, 8, 28, 9, 29)
>>>
Don't know about the speed though. Didn't have anything to
compare it took. You mentioned you do a lot of string concatenation
Double checking; do you know that in Python it's faster to append
the new string elements to a list and only then do a single
string concatenation of the list elements?
That is, do
terms = []
for x in data:
s = process_the_element(x)
terms.append(s)
s = "".join(data)
rather than
# this is slow if there are many string concatenations
s = ""
for x in data:
s = s + process_the_element(x)
Andrew
[EMAIL PROTECTED]
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