extracting numbers from a file, excluding words

[dawenliu]

Hi, I have a file with this content:

zzzz zzzzz zzz zzzzz
....
xxxxxxx xxxxxxxxxx xxxxx 34.215
zzzzzzz zz zzzz
....

"x" and "z" are letters.
The lines with "z" are trash, and only the lines with "x" are
important. I want to extract the number (34.215 in this case) behind
the letters x, and store it in a file.

The sentence "xxxxxxx xxxxxxxxxx xxxxx " is FIXED and KNOWN. The "z"
sentences are can vary. There are also unknown number of "z" lines.

Any suggestions will be appreciated.

[Kristina Kudriaðova]

1 Nov 2005 09:19:45 -0800, da******@gmail.com <da******@gmail.com>:

Hi, I have a file with this content:

zzzz zzzzz zzz zzzzz
...
xxxxxxx xxxxxxxxxx xxxxx 34.215
zzzzzzz zz zzzz
...

Hi,

I'd suggest doing this:

f = file('...')
for line in f:
if 'xxxxxxx xxxxxxxxxx xxxxx' in line:
var = float(line[len('xxxxxxx xxxxxxxxxx xxxxx'):].strip())
f.close()

[Steve Horsley]

Kristina Kudriašova wrote:

1 Nov 2005 09:19:45 -0800, da******@gmail.com <da******@gmail.com>:

Hi, I have a file with this content:

zzzz zzzzz zzz zzzzz
...
xxxxxxx xxxxxxxxxx xxxxx 34.215
zzzzzzz zz zzzz
...

Hi,

I'd suggest doing this:

f = file('...')
for line in f:
if 'xxxxxxx xxxxxxxxxx xxxxx' in line:
var = float(line[len('xxxxxxx xxxxxxxxxx xxxxx'):].strip())
f.close()

I think I prefer "if line.startswith('xxxxxxx xxxxxxxxxx
xxxxx'):" . Feels cleaner to me.

Steve

[Jeffrey Schwab]

Steve Horsley wrote:

Kristina Kudriašova wrote:

1 Nov 2005 09:19:45 -0800, da******@gmail.com <da******@gmail.com>:

Hi, I have a file with this content:

zzzz zzzzz zzz zzzzz
...
xxxxxxx xxxxxxxxxx xxxxx 34.215
zzzzzzz zz zzzz
...

Hi,

I'd suggest doing this:

f = file('...')
for line in f:
if 'xxxxxxx xxxxxxxxxx xxxxx' in line:
var = float(line[len('xxxxxxx xxxxxxxxxx xxxxx'):].strip())
f.close()

I think I prefer "if line.startswith('xxxxxxx xxxxxxxxxx xxxxx'):" .
Feels cleaner to me.

Especially if any "z" lines might include the magic pattern.

[Mike Meyer]

Kristina Kudriaðova <ri******@gmail.com> writes:

1 Nov 2005 09:19:45 -0800, da******@gmail.com <da******@gmail.com>:

Hi, I have a file with this content:

zzzz zzzzz zzz zzzzz
...
xxxxxxx xxxxxxxxxx xxxxx 34.215
zzzzzzz zz zzzz
...

Hi,

I'd suggest doing this:

f = file('...')
for line in f:
if 'xxxxxxx xxxxxxxxxx xxxxx' in line:
var = float(line[len('xxxxxxx xxxxxxxxxx xxxxx'):].strip())
f.close()

Alternatively:

start = len('xxxxxxx xxxxxxxxxx xxxxx')
for line in f:
if line.startswith('xxxxxxx xxxxxxxxxx xxxxx'):
var = float(line[start:].strip())

<mike
--
Mike Meyer <mw*@mired.org> http://www.mired.org/home/mwm/
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.

[Micah Elliott]

On Nov 01, Mike Meyer wrote:

Kristina Kudriaðova <ri******@gmail.com> writes:

1 Nov 2005 09:19:45 -0800, da******@gmail.com <da******@gmail.com>:

Hi, I have a file with this content:

zzzz zzzzz zzz zzzzz
...
xxxxxxx xxxxxxxxxx xxxxx 34.215
zzzzzzz zz zzzz
...

Hi,

I'd suggest doing this:

f = file('...')
for line in f:
if 'xxxxxxx xxxxxxxxxx xxxxx' in line:
var = float(line[len('xxxxxxx xxxxxxxxxx xxxxx'):].strip())
f.close()

Alternatively:

start = len('xxxxxxx xxxxxxxxxx xxxxx')
for line in f:
if line.startswith('xxxxxxx xxxxxxxxxx xxxxx'):
var = float(line[start:].strip())

To refine this even further, I'll add that 'xxx...' is an ugly pattern
to repeat, and prone to mistyping, so add a tempvar and apply DRY::

pattern = 'xxxxxxx xxxxxxxxxx xxxxx'
start = len(pattern)
for line in f:
if line.startswith(pattern):
var = float(line[start:].strip())

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