| Re: Where vs Histogram vs ?? [message #32570 is a reply to message #32526] |
Tue, 22 October 2002 17:26   |
Andrew Cool
Messages: 219
Registered: January 1996
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Senior Member |
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Stein Vidar Hagfors Haugan wrote:
>
> Andrew Cool <andrew.cool@dsto.defence.gov.au> writes:
>
>> Hello All,
>> index = Where(!database.year GE start_year AND $
>> !database.year LE end_year AND $
>> !database.day GE start_day AND $
>> !database.day LE end_day AND $
>> !database.beam GE start_beam AND $
>> !database.beam LE end_beam AND $
>> !database.half_hr GE start_half_hr AND $
>> !database.half_hr LE end_half_hr AND $
>> !database.WRF EQ WRF AND $
>> !database.FREQ EQ FREQ AND $
>> !database.parameter(nominated_parameter) NE
>> bad_data_value)
> [...]
>
> Given the above, could you perhaps try a multi-stage selection, e.g.,
>
> wrf_ok = !database.WRF EQ WRF
> wrf_freq_ok = !database.FREQ EQ FREQ AND temporary(wrf_ok)
> ;; By now you should have 1/12th of the data left!
> ;; Don't know how many bad_data_values you expect, the next one might
> ;; not gain much:
> wrf_freq_good =!database.parameter(nominated_parameter) NE bad_data_value $
> AND temporary(wrf_freq_ok)
>
> index1 = where(wrf_freq_good)
>
> ;; Build a new database on this subset (smaller than 1/12th),
> ;; continue with the rest of your searches...
>
Hello Stein,
I think your multistage selection using "AND Temporary(prev_stage)"
is the way for me. I'm rather enamoured with the use of the structure
in this database, and reluctant to give it up without a fight. It just
makes it so easy to query the database from the command line as well as
programatically.
Although arrays would probably be faster, I'll settle for a V2 rather
than
a Saturn V if it means I can keep the structures.
Thanks to everyone for their suggestions!
Andrew
------------------------------------------------------------ -----------------
Andrew D. Cool
Electromagnetics & Propagation Group
Intelligence, Surveillance & Reconnaissance Division
Defence Science & Technology Organisation
PO Box 1500, Edinburgh
South Australia 5111
Phone : 061 8 8259 5740 Fax : 061 8 8259 6673
Email : andrew.cool@dsto.defence.gov.au
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