Getting number of iteration

[Florian Lindner]

Hello,
when I'm iterating through a list with:

for x in list:

how can I get the number of the current iteration?

Thx,

Florian
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Re: Getting number of iteration

[Bill Mill]

On 5/6/05, Florian Lindner [EMAIL PROTECTED] wrote:
 Hello,
 when I'm iterating through a list with:
 
 for x in list:
 
 how can I get the number of the current iteration?

Python 2.4 and greater:

for n, x in enumerate(lst):
print iteration %d on element %s % (n, x)

Earlier:

n = 0
for x in lst:
print iteration %d on element %s % (n, x)
n += 1

And you shouldn't use list as a variable name; list() is a built-in
function which you'll clobber if you do.

Peace
Bill Mill
bill.mill at gmail.com
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Re: Getting number of iteration

[Bill Mill]

On 5/6/05, Bill Mill [EMAIL PROTECTED] wrote:
 On 5/6/05, Florian Lindner [EMAIL PROTECTED] wrote:
  Hello,
  when I'm iterating through a list with:
 
  for x in list:
 
  how can I get the number of the current iteration?
 
 Python 2.4 and greater:

ummm, make that 2.3 and greater. I always think things are more recent
than they are.

 
 for n, x in enumerate(lst):
 print iteration %d on element %s % (n, x)
 
 Earlier:
 
 n = 0
 for x in lst:
 print iteration %d on element %s % (n, x)
 n += 1
 
 And you shouldn't use list as a variable name; list() is a built-in
 function which you'll clobber if you do.
 
 Peace
 Bill Mill
 bill.mill at gmail.com

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Re: Getting number of iteration

[George Sakkis]

Florian Lindner wrote:

 Hello,
 when I'm iterating through a list with:

 for x in list:

 how can I get the number of the current iteration?

 Thx,

 Florianfor

in python 2.3+:

for i,x in enumerate(sequence):
print sequence[%d] = %s %(i,x)


George

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Re: Getting number of iteration

[Mike Meyer]

Bill Mill [EMAIL PROTECTED] writes:

 On 5/6/05, Florian Lindner [EMAIL PROTECTED] wrote:
 Hello,
 when I'm iterating through a list with:
 
 for x in list:
 
 how can I get the number of the current iteration?
 Earlier:

 n = 0
 for x in lst:
 print iteration %d on element %s % (n, x)
 n += 1

Just for the record, the old idiom was:

for n in xrange(len(lst)):
x = lst[n]
print iteration %d on element %s % (n, x)

mike
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Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.
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Re: Getting number of iteration

[Fredrik Lundh]

Mike Meyer wrote:

  n = 0
  for x in lst:
  print iteration %d on element %s % (n, x)
  n += 1

 Just for the record, the old idiom was:

 for n in xrange(len(lst)):
 x = lst[n]
 print iteration %d on element %s % (n, x)

it was?  of the following four solutions,

for n in xrange(len(lst)):
x = lst[n]
...

for n in range(len(lst)):
x = lst[n]
...

n = 0
for x in lst:
...
n += 1

for x, n in enumerate(lst):
...

the xrange solution tends to be the slowest, especially for
relatively short lists (up to a 1000 elements, or so).

the exact details vary somewhat between Python versions,
but the += solution is always a good choice, and the xrange
solution is almost always a bad choice.

/F



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