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20041029: IDV - jython method for adding dataset

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  • Subject: 20041029: IDV - jython method for adding dataset
  • Date: Sun, 31 Oct 2004 11:53:20 -0700
>From: "John Cartwright" <address@hidden>
>Organization: NOAA/NGDC
>Keywords: 200410292302.i9TN2tWI015323 IDV formula data

Hi John-

>Institution: NOAA
>Package Version: 1.1
>Operating System: Win2K sp4
>Hardware Information: Dell Optiplex GX260
>Inquiry: Hello,
>
>I'm trying to use a jython formula to create a new dataset.
>
>However, the display is never generated, visad just keeps processing. In the D
> ata Selector, I choose the formula, then click "Create Display"
>
>Here's the formula:
>===============================
>import math
>
>def generateTestField():
>   z = []
>   for i in range(0,32):
>      a = []
>      for j in range(0,32):
>        a.append( math.sin(i*j*.0174533))
>      z.append(a)
>   f = field(z)
>   return f
>================================
>
>
>Can you show me what I'm doing wrong?

I tried this under 1_1 and using the latest development version.
Since you are not providing lat/lon values for the field, the only
display that this would be meaningful for would be the Omni display.
In both versions, I was able to use that control do display the
image.  Also, if I tried something like a plan view contour, I
got the control, but nothing would be displayed since there are
no lat/lon values.  However, I did not get it just crunching away.
If that's what you got, let me know:

1) what did you provide for the name, formula and description 
fields for the formula?  It should be something like:

Name: test
Formula: generateTestField()
Descriptions: John's way cool formulas (options, will use the name
field as the default).

If you can get past that, here are some more suggestions:

If you change the jython to call the field function to:

   f = field("Longitude", "Latitude", "values", z)

you could display it over Africa. ;-)

To place it somewhere else, use the combination of one of the
JPythonMethods.makeDomain methods and the field method that
takes a set.

Don Murray
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