Re: Equivalent string.find method for a list of strings

[Steven Bethard]

jeremit0 wrote:
Steve Holden wrote:
If you want line numbers,. of course, then you can use
  for linenum, line in enumerate(myfile.readlines()):
      ...
Remember that true to Python's philosophy numbering will start at zero.
Is this any better than:
    lines = myfile.readlines()
    for linenum in xrange(len(lines)):
        # Do stuff with lines[linenum] ...
Well, if you use lines[linenum] often in that code, it'll be more 
efficient to use enumerate (or bind lines[linenum] to a name, which is 
basically what enumerate is doing for you).  Given the file test.py:

--------------------------------------------------
def elines(lines):
    for linenum, line in enumerate(lines):
        x = linenum
        y = line
        z = line
def xlines(lines):
    for linenum in xrange(len(lines)):
        x = linenum
        y = lines[linenum]
        z = lines[linenum]
--------------------------------------------------
Here's what I get with timeit:
[D:\Steve]$ python -m timeit -s"lines = range(10000); import test" 
"test.elines(lines)"
100 loops, best of 3: 2.85 msec per loop

[D:\Steve]$ python -m timeit -s"lines = range(10000); import test" 
"test.xlines(lines)"
100 loops, best of 3: 3.18 msec per loop

The other thing worth noting is that enumerate will work with any 
iterable, while your xrange technique won't.  Try:
    for linenum, line in enumerate(myfile):
        ...
and
    for linenum in xrange(len(myfile)):
        line = myfile[linenum]
        ...
and see what kind of cool errors you get with the xrange solution. :)

STeVe
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