readlines with line number support?

[Nikhil]

Hi,

I am reading a file with readlines method of the filepointer object
returned by the open function. Along with reading the lines, I also need
to know which line number of the file is read in the loop everytime.
I am sure, the line should have the property/attribute which will say
the line number of the file.

If there is none, do I have to end up using the counter in the loop?

fp = open("file", "r")
lineno = 0
for line in fp.readlines():
print "line number: " + lineno + ": " + line.rstrip()
lineno = lineno + 1

--

Thanks,
Nikhil

[Paul McNett]

Untested:

for lineno, line in enumerate(open("file")):
print "line number: %s : %s" % (idx, line.rstrip())

Note the other stylistic changes, too.

HTH.
Paul

[Arnaud Delobelle]

Nikhil <mni...@gmail.com> writes:

The standard Python way is using enumerate()

for i, line in enumerate(fp):

print "line number: " + lineno + ": " + line.rstrip()

--
Arnaud

[Nikhil]

Oh I did not know enumerate can be used. Thanks Paul and Arnaud.
I will try this.

[Nikhil]

[Nikhil]

Arnaud Delobelle wrote:

> The standard Python way is using enumerate()
>
> for i, line in enumerate(fp):
> print "line number: " + lineno + ": " + line.rstrip()
>

I guess you meant to say :

for lineno, line in enumerate(fp):

print "line number: " + lineno + ": " + line.rstrip()

Thanks.

[Arnaud Delobelle]

Nikhil <mni...@gmail.com> writes:

Yes!

--
Arnaud

[pyt...@bdurham.com]

Arnaud,

>> Is there any way to have enumerate() start at 1 vs. 0?
>>
>> The problem with starting at 0 is that many things in the real world
>> begin at 1 - like line numbers or labels in a list.

> I suppose you could redefine enumerate to support an optional argument:
>
> from itertools import izip, count
>
> def enumerate(iterable, start=0):
> return izip(count(start), iterable)
>
> >>> list(enumerate('spam', 1))
> [(1, 's'), (2, 'p'), (3, 'a'), (4, 'm')]

Brilliant!!

Thank you,
Malcolm