filter in for loop

[GHZ]

I would like to say something like:

for x in l if <expression>:
<do something>

e.g.

for filename in os.listdir(DIR) if filename[-4:] == '.xml':
<do something>


instead of having to say:

for filename in os.listdir(DIR) :
if filename[-4:] == '.xml':
<do something>

or

for filename in (f for f in os.listdir(DIR) if f[-4] == '.xml'):
<do something>


is there a shortcut I'm missing?

[Bruno Desthuilliers]

Re: filter in for loop

GHZ a écrit :

I would like to say something like:
>
for x in l if <expression>:
<do something>
>
e.g.
>
for filename in os.listdir(DIR) if filename[-4:] == '.xml':
<do something>
>
>
instead of having to say:
>
for filename in os.listdir(DIR) :
if filename[-4:] == '.xml':
<do something>
>
or
>
for filename in (f for f in os.listdir(DIR) if f[-4] == '.xml'):
<do something>
>
>
is there a shortcut I'm missing?

Not AFAIK, and I sometimes regret it - but the first alternative is good
enough IMHO.

<ot>
I'd rather use os.path.splitex t or str.endswith than subscript, but YMMV.
</ot>

[Chris]

Re: filter in for loop

On Aug 28, 12:20 pm, GHZ <geraint.willi. ..@gmail.comwro te:

I would like to say something like:
>
for x in l if <expression>:
    <do something>
>
e.g.
>
for filename in os.listdir(DIR) if filename[-4:] == '.xml':
    <do something>
>
instead of having to say:
>
for filename in os.listdir(DIR) :
    if filename[-4:] == '.xml':
        <do something>
>
or
>
for filename in (f for f in os.listdir(DIR) if f[-4] == '.xml'):
    <do something>
>
is there a shortcut I'm missing?

from glob import glob
from os import path
DIR = 'PathToFiles'
EXT = '*.xml'

for filename in glob(path.join( DIR, EXT)):
print filename

[Timo]

Re: filter in for loop

On 28 elo, 13:20, GHZ <geraint.willi. ..@gmail.comwro te:

>
is there a shortcut I'm missing?

(Adding to Bruno's comment)

This kind of style provides a reusable filter/generator-function and
as a bonus, the for-loop becomes easier to understand.

from os.path import abspath
from glob import iglob

def ipathnames(patt ern):
return (abspath(n) for n in iglob(pattern))

for xmlfile in ipathnames('*.x ml'):
<do something>

-- timo

[Jerry Hill]

Re: filter in for loop

On Thu, Aug 28, 2008 at 6:20 AM, GHZ <geraint.willia ms@gmail.comwro te:

is there a shortcut I'm missing?

Well, there's another way to do it, using the filter built in function:

for filename in filter(lambda f:f.endswith('. xml'), os.listdir('.') ):
print filename

You can do the same thing with itertools.ifilt er if you need to deal
with arbitrary iterables. I think your first example of:

for filename in os.listdir('.') :
if filename.endswi th('.xml'):
<do something>

Is the most readable though.

--
Jerry

[Matthew Woodcraft]

Re: filter in for loop

GHZ <geraint.willia ms@gmail.comwri tes:

I would like to say something like:
>
for filename in os.listdir(DIR) if filename[-4:] == '.xml':
<do something>
>
>
instead of having to say:
>
for filename in os.listdir(DIR) :
if filename[-4:] == '.xml':
<do something>

If the reason you don't like this one is the extra indentation, one
possibility is

for filename in os.listdir(DIR) :
if filename[-4:] != '.xml':
continue
<do something>

-M-

[Emile van Sebille]

Re: filter in for loop

Jerry Hill wrote:

On Thu, Aug 28, 2008 at 6:20 AM, GHZ <geraint.willia ms@gmail.comwro te:

>is there a shortcut I'm missing?

>

import glob

Emile