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]

Re: readlines with line number support?

Nikhil wrote:

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

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]

Re: readlines with line number support?

Nikhil <mnikhil@gmail. comwrites:

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

The standard Python way is using enumerate()

for i, line in enumerate(fp):
print "line number: " + lineno + ": " + line.rstrip()

--
Arnaud

[Nikhil]

Re: readlines with line number support?

Arnaud Delobelle wrote:

Nikhil <mnikhil@gmail. comwrites:
>

>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

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

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

[Nikhil]

Re: readlines with line number support?

Arnaud Delobelle wrote:

Nikhil <mnikhil@gmail. comwrites:
>

>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

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

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

[Nikhil]

Re: readlines with line number support?

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]

Re: readlines with line number support?

Nikhil <mnikhil@gmail. comwrites:

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()

Yes!

--
Arnaud

[python@bdurham.com]

enumerate() values starting at 1 vs. 0

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(itera ble, start=0):
return izip(count(star t), iterable)
>

>>list(enumerat e('spam', 1))

[(1, 's'), (2, 'p'), (3, 'a'), (4, 'm')]

Brilliant!!

Thank you,
Malcolm