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[IDV #GNJ-327394]: IDV - text point data files; time versus value plots

Hi Stu-

> Institution: UNAVCO
> Package Version: 2.1
> Operating System: Linux and others
> Hardware Information: x86
> Inquiry: The Dashboard - Data Chooser - Data Source Type shows a type of Text 
> point data file.  What is the format for such a file?  Can it have multiple 
> parameters (fields) at each location? Can it have multiple times?

The format is the VisAD Text file format.  At this point, it is
only used for point data, but the VisAD text format also supports
grids and hopefully we can add that in the future (as well as your
text grid format).  The format look like:

(index) -> (Time,Latitude,Longitude,Altitude,PSL,GUS,SPD,DIR,TD,T)
Time[fmt="yyyy-MM-dd HH:mm:ss"],Latitude[unit="deg"],Longitude[unit="degrees 
west"],Altitude[unit="m"],PSL[unit="hPa"],GUS[unit="m.s-1"],SPD[unit="m/s"],DIR[uni
t="deg"],TD[unit="celsius"],T[unit="celsius"]
2007-01-07 16:00:00Z,32.9,117.1,145.0,1026.1,NaN,0.0,0.0,-2.8,12.8
2007-01-07 16:00:00Z,48.3,92.5,341.0,1003.7,NaN,1.5,170.0,-2.0,-0.99
2007-01-07 16:00:00Z,36.8,98.7,449.0,1024.0,12.4,9.8,330.0,-3.0,3.0
2007-01-07 16:00:00Z,44.3,121.2,938.0,1030.1,NaN,2.1,110.0,-3.3,-1.7
2007-01-07 16:00:00Z,15.1,-145.7,66.0,1011.8,NaN,7.2,100.0,23.9,26.0
2007-01-07 16:00:00Z,43.4,99.8,616.0,1021.0,NaN,9.3,290.0,-8.9,-2.8
2007-01-07 16:00:00Z,48.1,69.6,5.0,NaN,17.0,13.9,290.0,-5.0,1.0
2007-01-07 16:00:00Z,47.3,54.0,16.0,NaN,17.0,14.4,230.0,3.0,4.0
2007-01-07 16:00:00Z,45.8,62.7,2.0,NaN,NaN,12.9,290.0,-0.99,4.0
2007-01-07 16:00:00Z,49.8,64.3,53.0,NaN,12.9,8.2,290.0,0.01,2.0
2007-01-07 16:00:00Z,52.1,111.5,791.0,NaN,NaN,5.1,160.0,-14.0,-10.0
2007-01-07 16:00:00Z,50.5,59.6,6.0,NaN,NaN,6.7,300.0,1.0,1.0
2007-01-07 16:00:00Z,49.7,54.8,92.0,NaN,15.4,10.8,240.0,1.0,3.0
2007-01-07 16:00:00Z,47.4,72.8,169.0,NaN,NaN,3.6,300.0,-7.0,-0.99
2007-01-07 16:00:00Z,47.2,60.1,26.0,NaN,26.7,22.6,280.0,0.01,3.0
2007-01-07 16:00:00Z,49.4,109.0,1078.0,NaN,NaN,5.1,220.0,-14.0,-12.0
2007-01-07 16:00:00Z,46.4,62.0,11.0,NaN,20.1,15.9,290.0,0.01,4.0
2007-01-07 16:00:00Z,52.1,101.2,335.0,NaN,NaN,5.1,220.0,-14.0,-11.0
2007-01-07 16:00:00Z,47.0,70.8,5.0,NaN,9.3,6.7,240.0,NaN,NaN
2007-01-07 16:00:00Z,50.3,122.7,204.0,NaN,NaN,0.0,0.0,-0.99,0.01
2007-01-07 16:00:00Z,49.8,114.9,1137.0,NaN,12.3,7.2,150.0,-6.0,-4.0
2007-01-07 16:00:00Z,49.1,61.7,4.0,NaN,18.0,13.4,300.0,1.0,3.0
2007-01-07 16:00:00Z,53.2,99.3,223.0,NaN,NaN,4.1,290.0,-12.0,-10.0
2007-01-07 16:00:00Z,49.1,116.5,646.0,NaN,NaN,1.0,290.0,-2.0,-2.0
2007-01-07 16:00:00Z,54.8,112.0,565.0,NaN,NaN,2.1,170.0,-14.0,-12.0
2007-01-07 16:00:00Z,50.9,127.6,17.0,NaN,NaN,5.7,210.0,NaN,8.0
2007-01-07 16:00:00Z,52.2,127.5,32.0,NaN,17.0,11.8,210.0,4.0,7.0.......

(this was produced by loading in surface obs data and saving it
from the Point List control using the File->Save->Export Table)

You can have multiple times for a single station.  Basically, it
is a list of comma separated values with two lines of text at the
top that give it the special sauce needed for the IDV to interpret.
It looks like the link to the documentation for this format is
bad on the VisAD homepage, otherwise, I'd point you there.



> Can the IDV plot a graph of time versus field value at one location, from a 
> point data file? (other than in the omni display). If so, what file format is 
> used?

Not at present.  The hooks are all there to use the graphing facility,
but the time series plot does not understand how to parse the
PointObs Field to get the data.  If you'd like to tackle this, let
us know and we can point you to the appropriate classes.  Otherwise,
we will probably be looking at this later this year when we start
working with the THREDDS group on accessing remote point data.

Don


Ticket Details
===================
Ticket ID: GNJ-327394
Department: Support IDV
Priority: Normal
Status: Open