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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
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Hi Paul -- I'm not clear on the logic of "(if temp == NaN) then compute WetBulb"...or am I mis-reading this? Can you send me (off-line?) your web bulb computation formula? I'd like to see what additional logic is in there that prevents you from using VisAD "built-in" arithmetic. (I'm always looking for ideas for new functions to put into JPythonMethods). tom On Mon, Dec 9, 2013 at 3:59 PM, Paul Graham <meteorpaul@xxxxxxxxx> wrote: > Hi Tom, > > Thanks for your help. I figured out a method after some experimentation and > realised I could not use the visad logic. My algorithm works point-wise, > which requires having to step through each point individually. Essentially, > I modified existing code for substitution, found in IDV's Jython library: > > def wetbulb(temp,dewpt): > from java.lang import Math > tempData = temp.clone(); > dewptData = dewpt.clone(); > presData = extractPressureFromNWPGrid(tempData); > wetbulbData = temp.clone(); > if (GridUtil.isTimeSequence(tempData)): > for t in range(tempData.getDomainSet().getLength()): > tempValues = tempData[t] > dewptValues = dewptData[t] > presValues = presData[t] > wetbulbRangeObj = wetbulbData.getSample(t) > newValues = wetbulbRangeObj.getFloats(0) > print "Processing wetbulb temperature for time ", t > for i in range(len(tempValues)): > if(str(float(tempValues[i].getValue()))!='nan'): > newValues[0][i] = > findwetbulb(kelvinToCelcius(tempValues[i].getValue()),kelvinToCelcius(dewptValues[i].getValue()),presData[i].getValue()) > wetbulbRangeObj.setSamples(newValues,1) > wetbulbData = newUnit(noUnit(wetbulbData),'Wetbulb temperature in > celcius','C') > return wetbulbData > > > Paul > > > > > On 10 December 2013 01:12, Tom Whittaker <whittaker@xxxxxxxx> wrote: >> >> Hi Paul -- >> >> If your function has no logic that needs to be applied to each point, >> then if the data were read in via the IDV they would be "VisAD Data >> objects" and you should just be able to do something like: >> >> a = b + c - d >> >> where "b", "c" and "d" are 3D Data objects (or maybe 4D if they >> include "time") and it will do the computation on every point. and put >> the result in "a" (creating a new Data object with characteristics >> like that of "b" (the first object in the computation). >> >> If you have logic, then you might have to iterate over every point...I >> say "might" because sometimes some of the built-in methods like "mask" >> can be used to simulate logic. >> >> Hope that helps. >> >> tom >> >> >> >> On Sun, Dec 8, 2013 at 9:39 PM, Paul Graham <meteorpaul@xxxxxxxxx> wrote: >> > Hi IDV'ers, >> > >> > I have written a Jython function which takes temperature, dewpoint and >> > pressure as arguments and evaluated at each point in a 3d domain to >> > calculate the wet bulb temperature. What is the best way using Jython >> > to >> > iterate over my domain so I can set the wetbulb result for each point? >> > Eg. wetbulbresult[i][j][k] = >> > findwetbulb(temperature[i][j][k],dewpoint[i][j][k],pressure[i][j][k]), >> > where i,j are subscripts for the latitude and longitude and k for the >> > height. >> > >> > Thanks in advance, >> > >> > Paul >> > _______________________________________________ >> > idvusers mailing list >> > idvusers@xxxxxxxxxxxxxxxx >> > For list information, to unsubscribe, visit: >> > http://www.unidata.ucar.edu/mailing_lists/ >> >> >> >> -- >> Tom Whittaker >> University of Wisconsin-Madison >> Space Science & Engineering Center (SSEC) >> Cooperative Institute for Meteorological Satellite Studies (CIMSS) >> 1225 W. Dayton Street >> Madison, WI 53706 USA >> ph: +1 608 262 2759 > > -- Tom Whittaker University of Wisconsin-Madison Space Science & Engineering Center (SSEC) Cooperative Institute for Meteorological Satellite Studies (CIMSS) 1225 W. Dayton Street Madison, WI 53706 USA ph: +1 608 262 2759
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