20040127: 20040127: methods to export data in IDV question

>From: Jeffrey Buler <address@hidden>
>Organization: University of Southern Mississippi
>Keywords: 200401272246.i0RMkcp2006629 IDV radar printing

Hi Jeff-

>Thank you for the formula!  I was able to cut and paste the formula into the 
>Jython library editor and execute it on my data.  I get an ouput that is 
>exactly what I was looking for.  I noticed that in line 21 one can adjust 
>which range bins to output.  That is handy.  

Oops, I was working on this as I was answering and forgot to change the
code to output the entire sweep.  The loop should have been from 0 to c,
not 0 to 10.  

>However, there is only one ray (one azimuth) in the output.  I've tried to 
>decipher the formula to see where the loop to iterate the remaining rays is 
>located but cant find it (line 14?) and cannot get the rest of the rays in the
>sweep to output.  Would you please troubleshoot this for me? I am using IDV 
>version 1.1b2 in Windows XP. 

Here's a more annotated version:

import sys;
sys.add_package('visad');
sys.add_package('visad.util');
sys.add_package('ucar.visad');
def printField(a,filename="foo"):
  from visad import RealTupleType as rt
  from visad.util import DataUtility as du
  from ucar.visad.Util import *
  # open a file for writing
  file = open(filename,"w")
  mydu = du()
  # data has format like: 
  #   (Time -> ((Range, Azimuth, Elevation_Angle) -> Reflectivity))
  # get the outer time domain
  tdom = a.getDomainSet()
  l = tdom.getLength()
  # iterate over time domain
  for j in range(0,l):
    # write out the timestamp
    file.write(str(mydu.getSample(tdom, j))+"\n")
    #get first sweep
    b = a[j]
    # print out the datatype
    file.write(str(b.getType())+"\n")
    # dom will be (Range, Azimuth, Elevation_Angle)
    dom = b.getDomainSet()
    # convert to lat/lon/alt.  This does not account for
    # refraction
    lldom = convertDomain(dom, rt.LatitudeLongitudeAltitude,None)
    c = dom.getLength()
    # now loop over each point
    n = 0
    line = ""
    for i in range(0,c):
        # point in (Range, Azimuth, Elevation_Angle) space
        point = mydu.getSample(dom, i)
        # point in (Latitude, Longitude, Altitude) space
        llpoint = mydu.getSample(lldom,i)
        # value for data
        value = b[i].getValue()
        # format output - buffers 10 points before printing
        if n < 10:
           line = line+str(point)+" "+str(llpoint)+" = "+str(value)+"\n"
           n = n + 1
        else:
          # write it out to the file
          file.write(line)
          n = 0
          line=""
  file.close()
  return a

>
>Also, what spheroid did you use to generate lat&long?

We are using an earth radius of 6367681.04774543 meters for
our calculations.  We are under the process of reviewing this
calculation to account for refraction. 

Don
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