[Tutor] how to track an entry in a large text file

[Oscar Benjamin]

On 16 January 2013 21:22, 3n2 Solutions <3n2solutions at gmail.com> wrote:
> Say I have a text file (example below) that has multiple records with
> the same format but not always the same number of lines.  Each record
> is separated by the line that starts with “Examining file” as in below
> example. If you notice, the 3D Val is not there for the second record.
> How do I report that the “3D Val” is not present for that particular
> record “8866W2310089.txt”?
> Thanks to Alan for his reply.

I don't follow what you mean by 'How do I report that the “3D Val” is
not present for that particular
record “8866W2310089.txt”?'

The obvious answer would be (assuming the filename is currently set to
“8866W2310089.txt”):
    print('3D Val not present in %s' % filename)

I wonder if your actual question is:
1) How do I detect that it is not present? - check for a line starting
with '3D' while reading the file.
2) How do I mark it is not being present in my data structure? -
depends what kind of data structure you are using. A common idiom
would be to simply use the value None as a place-holder for situations
where the value is not supplied.
3) Something else...

>
> Examining file: 5521W2310000.txt
>
> Duration                 :      0h : 59m
> First meas : week   :  86     :   1721
> Last  meas : week   :  89     :   1721
>
> Min val           :     15
> Max val         :     18
> 3D             :   3600  100.0%
>
> summary         Total  Missed    Rate
> epoch1                :        1378       0       0\1000
> epoch2                :        2154       1       0\1000
>
>
>
> Examining file: 8866W2310089.txt
>
> Duration                 :      0h : 59m
> First meas : week   :  87     :   1721
> Last  meas : week   :  84     :   1721
>
> Min val           :     16
> Max val         :     19
>
> summary         Total  Missed    Rate
> epoch1                :        1378       0       0\1000
> epoch


Oscar