[Tutor] Uniform 'for' behavior for strings and files
alan.gauld at btinternet.com
Tue Jun 10 02:14:27 CEST 2008
"Shrutarshi Basu" <technorapture at gmail.com> wrote
> for item in block:
> where block is a file, then item becomes each line of the file in
> But if block in a large string (let's say the actual text that was
> the file), item becomes each character at a time.
Correct because for iterates over a sequence. It will return whatever
the unit of sequence is. So the challenge is to make the sequence
represent the data in the units you need.
So to make a long string return lines rather than characters you
need to break the string into lines. The easiest way to do that is
using the split() method:
for line in block.read().split():
But of course for files you can just read the lines directly - or
indirectly using readlines().
> have a uniform iteration irrespective of whether block is a file or
> string (ideally one \n-delimited line at a time)?
The for loop is uniform, it is just that the sequence unit is
> default for behavior is being problematic. I could turn the whole
> into a string first, but that might cause problems with large files.
You could write a generator function that returned blocks. That
would fit your problem quite well and be memory friendly as well.
That way the for would work exactly as you require.
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