On Tue, 29 Dec 2009 01:35:41 -0500, Steven D'Aprano
<ste...@remove.this.cybersource.com.au> wrote:
On Tue, 29 Dec 2009 00:49:50 -0500, John Posner wrote:
On Sun, 27 Dec 2009 09:44:17 -0500, joy99 <subhakolkata1...@gmail.com>
wrote:
Dear Group,
I am encountering a small question.
Suppose, I write the following code,
input_string=raw_input("PRINT A STRING:")
string_to_word=input_string.split()
len_word_list=len(string_to_word)
if len_word_list>9:
rest_words=string_to_word[9:]
len_rest_word=len(rest_words)
if len_rest_word>9:
remaining_words=rest_words[9:]
Here's an issue that has not, I think, been addressed in this thread.
The OP's problem is:
1. Start with an indefinitely long string.
2. Convert the string to a list, splitting on whitespace.
3. Repeatedly return subslices of the list, until the list is exhausted.
This thread has presented one-chunk-at-a-time (e.g. generator/itertools)
approaches to Step #3, but what about Step #2? I've looked in the Python
documentation, and I've done some Googling, but I haven't found a
generator version of the string function split(). Am I missing
something?
"Indefinitely long" doesn't mean you can't use split.
But if you want a lazy splitter, here's a version which should do what
you want:
def lazy_split(text):
accumulator = []
for c in text:
if c in string.whitespace:
if accumulator:
yield ''.join(accumulator)
accumulator = []
else:
accumulator.append(c)
if accumulator:
yield ''.join(accumulator)
Thanks -- I coded a similar generator, too. Yours handles the corner cases
and end-of-string more elegantly, so I won't share mine. :-)
Other alternatives are to use a regex to find runs of whitespace
characters, then yield everything else; or to use the itertools.groupby
function.
Yup, that approach occurred to me as I was falling asleep last night (OMG,
get a life, buddy!):
def groupby_split(text):
whitespace_grouper = itertools.groupby(
text,
lambda(c): c not in string.whitespace)
for boolval, group_iter in itertools.ifilter(
lambda pair: pair[0] == True,
whitespace_grouper):
yield "".join(group_iter)
Tx,
John
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