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[McIDAS #GXY-149445]: Read order of MD file record



Hi Kwan,

re:
> I would like to know if one can reverse the read order of data records
> residing in an MD point file when displaying the data using the PTDISP
> command.  The reason I would like to do that is that it would ensure PTDISP
> to always plot the latest data record if a time range is specified.  As an
> example, if I want to plot METARs between 18Z and 19Z, and the following
> stations reported data at the following HMS,
> 
> Station A   Station B
> 1845Z        1800Z
> 1853Z        1830Z
> 1900Z        1900Z
> 
> EG; PTDISP RTPTSRC/SFCHOURLY 1 PAR=WIND[KTS] PRE[MB] GUS[KPH] WXC1 HMS
> LSI=18 9 9 13 9 COL=8 8 8 8 8 OFF=X X -10 4 3 4 0 -20 0 10 FORMAT=FLAG K2
> I3 WXCM I6 *SEL='HMS 18:00:00 19:00:00*' LOC=o 8 4
> 
> PTDISP will display 1845Z data for station A and 1800Z data for station B,
> because PTDISP apparently would display the first record it encounters in
> the MD file within the requested time range.  If I could read the MD file
> starting from the last (and latest) record in the file, PTDISP would be
> able to display the 1900Z data for both station A and B.  An alternative
> would be to reverse the record order in the MD file so that the last (and
> latest) record is saved first.  Do you think this can be accomplished?

You could add the DECLut=NO keyword sequence that will result in all
observations being plotted.

As far as changing the search order that PTDISP uses for MD files, then
I'm almost positive that the answer is no.  I imagine that one could
write a special purpose routine that might do a reverse search, but
that would take a lot of time by an expert.

It may be possible to copy select observations out of one MD file into
another one and then use the resultant file... just musing out loud :-)


Cheers,

Tom
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Ticket Details
===================
Ticket ID: GXY-149445
Department: Support McIDAS
Priority: Normal
Status: Closed
===================
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