strange issue with deleting a list of variables

From: Brian Medeiros <brianpm_at_nyahnyahspammersnyahnyah>
Date: Wed Sep 25 2013 - 11:21:31 MDT

Hi NCLers,

I've got a silly problem with deleting a list of variables (i.e., using delete( [/ /] ) ). It works great, except for this apparently bizarre special case:

If a variable is returned from a custom function that has been called with the argument referencing another variable's coordinate variable, then delete will not remove the returned variable.

I know, sounds crazy. Here's a test script, that I've tested with Mac OSX (10.8.5), NCL 6.1.2 and on Yellowstone with NCL 6.2.0-25Sep2013_0234:

function gen_area_wgt(lat)
begin
  ;; wgt is the latitude weight
  wgt = lat
  wgt!0 = "lat"
  wgt&lat = wgt
  wgt = (/cos( 4.*atan(1.)*wgt/180.) /)
  return(wgt)
end

begin

    lat = fspan( -90.d, 90.d, 91 )

    z = new( dimsizes( lat ), float )
    z!0 = "lat"
    z&lat = lat

    wgt = z&lat
    wgt!0 = "lat"
    wgt&lat = wgt
    wgt = (/ cos( 4. * atan(1.) * wgt / 180. ) /) ;; This one gets deleted normally.

    wgt2 = gen_area_wgt( lat ) ;; This one gets deleted normally.

    wgt3 = gen_area_wgt( z&lat ) ;; THIS ONE PERSISTS THROUGH DELETE (when using list as arg to delete).
    
    print( "(pre) is variable: " + str_join( (/ isvar("z"), isvar("wgt"), isvar("wgt2"), isvar("wgt3")/) , ", ") )
    
    delete( [/lat, z, wgt , wgt2, wgt3 /] )
    
    print( "(post) is variable: " + str_join( (/isvar("z"), isvar("wgt"), isvar("wgt2"), isvar("wgt3")/) , ", ") )

    ;; BUT WE CAN DELETE IT SEPARATE FROM THE LIST:
    delete( wgt3 )
    print("final check: " + isvar("wgt3") )

end

Any thoughts? Thanks,

.brian
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Received on Wed Sep 25 11:20:41 2013

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