extract certain values from file with re

[Matteo]

Fabian Braennstroem wrote:
> Hi,
>
> I would like to remove certain lines from a log files. I had
> some sed/awk scripts for this, but now, I want to use python
> with its re module for this task.
>
> Actually, I have two different log files. The first file looks
> like:
>
>    ...
>    'some text'
>    ...
>
>        ITER I----------------- GLOBAL ABSOLUTE RESIDUAL -----------------I  I------------ FIELD VALUES AT MONITORING LOCATION  ----------I
>         NO    UMOM     VMOM     WMOM     MASS     T EN     DISS     ENTH       U        V        W        P       TE       ED        T
>          1  9.70E-02 8.61E-02 9.85E-02 1.00E+00 1.61E+01 7.65E+04 0.00E+00  1.04E-01-8.61E-04 3.49E-02 1.38E-03 7.51E-05 1.63E-05 2.00E+01
>          2  3.71E-02 3.07E-02 3.57E-02 1.00E+00 3.58E-01 6.55E-01 0.00E+00  1.08E-01-1.96E-03 4.98E-02 7.11E-04 1.70E-04 4.52E-05 2.00E+01
...

Just a thought, but what about using exceptions - something like:

for line in logfile:
  vals=line.split()
  try:
    no=int(vals[0])
    # parse line as needed
  except ValueError:         #first item is not a number
    pass                           # ignore line, or parse it
separately

Coming from C++, using exceptions in this way still feels a bit creepy
to me, but I've been assured that this is very pythonic, and I'm slowly
adopting this style in my python code.

Parsing the line can be easy too:
   (umom,vmom,wmom,mass...) = map(float,vals[1:])


-matt