Hello,
Can anyone point me towards an article or explain
how to properly alter a list as well as iterate
on its items? For example:
input:
word = ["albert", "likes", "surfing!"]
for word in sentence:
word += "foo"
result:
word = ["albertfoo" , "likesfoo", "surfingfoo "]
Thanks,
Derek Basch
_______________ _______________ ____
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On Tue, 25 May 2004 12:57:32 -0700, Derek Basch wrote: Hello,
Can anyone point me towards an article or explain how to properly alter a list as well as iterate on its items? For example:
input:
word = ["albert", "likes", "surfing!"]
for word in sentence: word += "foo"
result:
word = ["albertfoo" , "likesfoo", "surfingfoo "]
word = ["albert","likes ","surfing! "]
you could do it with a map:
word = map(lambda x: x + "foo", words)
or with a list comprehension:
word = [x + "foo" for x in words]
Most of the time this is done without
a loop at all as follows:
word = ["albert", "likes", "surfing!"]
word = [x+"foo" for x in word]
word = [""albertfoo ", "likesfoo", "surfing!fo o"]
Much of what you use loops for in other
languages you don't need in Python. List
comprehensions is a very powerful tool and it is
worth spending some time learning about.
Some tutorial links: http://www.secnetix.de/~olli/Python/...rehensions.haw http://www.cosc.canterbury.ac.nz/~greg/python/listcomp/
Larry Bates
Syscon, Inc.
"Derek Basch" <db****@yahoo.c om> wrote in message
news:ma******** *************** **************@ python.org... Hello,
Can anyone point me towards an article or explain how to properly alter a list as well as iterate on its items? For example:
input:
word = ["albert", "likes", "surfing!"]
for word in sentence: word += "foo"
result:
word = ["albertfoo" , "likesfoo", "surfingfoo "]
Thanks, Derek Basch
_______________ _______________ ____ Do you Yahoo!? Friends. Fun. Try the all-new Yahoo! Messenger. http://messenger.yahoo.com/
Derek Basch <db****@yahoo.c om> wrote in message news:<ma******* *************** *************** @python.org>... Hello,
Can anyone point me towards an article or explain how to properly alter a list as well as iterate on its items? For example:
input:
word = ["albert", "likes", "surfing!"]
for word in sentence: word += "foo"
result:
word = ["albertfoo" , "likesfoo", "surfingfoo "]
Thanks, Derek Basch
..
..
..
An solution No. 992345739219242 .... is:-): from operator import add word = ["albert", "likes", "surfing!"] map(add,word,['foo']*len(word))
['albertfoo', 'likesfoo', 'surfing!foo']
Regards
Peter
Derek Basch wrote: Can anyone point me towards an article or explain how to properly alter a list as well as iterate on its items? For example:
input:
word = ["albert", "likes", "surfing!"]
for word in sentence: word += "foo"
result:
word = ["albertfoo" , "likesfoo", "surfingfoo "]
Note that the solutions presented so far do *not* modify the list in place.
This is important if you keep references to the list elswhere. For example: backup = sample = ["alpha", "beta", "gamma"] sample = map(lambda x: x + ".suffix", sample) sample is backup
False sample = [x + ".suffix" for x in sample] sample is backup
False
Here are two ways to achieve inplace modification:
backup = sample = ["alpha", "beta", "gamma"] for i, x in enumerate(sampl e):
.... sample[i] = x + ".suffix"
.... sample is backup
True
backup = sample = ["alpha", "beta", "gamma"] sample[:] = [x + ".suffix" for x in sample] sample is backup
True
Here the [:] slice on the left makes the difference.
Peter This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
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