[ferret_users] Bug in sampleXY....?

[Paul Young <paul.j.young@xxxxxxxx>]

Hi all,

I've had a couple of issues with sampleXY that I thought I should report. (Sorry if this has been noted, but I can't seem to access the email archives on the website)

1. Longitudes cannot be negative it seems (i.e. negative degrees_east). E.g., with coads_climatology:

yes? let dat = samplexy(sst,{160,180,-20},{0,0,0})				!3rd longitude is 20W
yes? list dat
            VARIABLE : SAMPLEXY(SST,{160,180,-20},{0,0,0})
            FILENAME : coads_climatology.cdf
            FILEPATH : /usr/local/ferret/data/
            SUBSET   : 3 by 12 points (X-TIME)
                     1      2      3    
                     1      2      3
16-JAN      /  1:  29.09  28.36   ....
15-FEB      /  2:  29.09  28.38   ....
17-MAR      /  3:  29.01  28.00   ....
16-APR      /  4:  29.14  27.99   ....
16-MAY      /  5:  29.19  28.41   ....
16-JUN      /  6:  29.36  28.23   ....
16-JUL      /  7:  29.00  28.52   ....
16-AUG      /  8:  29.06  28.51   ....
15-SEP      /  9:  29.24  28.26   ....
16-OCT      / 10:  29.04  28.33   ....
15-NOV      / 11:  29.07  28.76   ....
16-DEC      / 12:  29.04  28.27   ....


yes? let dat = samplexy(sst,{160,180,340},{0,0,0})					!Convert 3rd longitude to positive value
yes? list dat
            VARIABLE : SAMPLEXY(SST,{160,180,340},{0,0,0})
            FILENAME : coads_climatology.cdf
            FILEPATH : /usr/local/ferret/data/
            SUBSET   : 3 by 12 points (X-TIME)
                     1      2      3    
                     1      2      3
16-JAN      /  1:  29.09  28.36  26.90
15-FEB      /  2:  29.09  28.38  27.42
17-MAR      /  3:  29.01  28.00  27.87
16-APR      /  4:  29.14  27.99  28.14
16-MAY      /  5:  29.19  28.41  27.63
16-JUN      /  6:  29.36  28.23  26.18
16-JUL      /  7:  29.00  28.52  24.82
16-AUG      /  8:  29.06  28.51  24.76
15-SEP      /  9:  29.24  28.26  24.94
16-OCT      / 10:  29.04  28.33  25.88
15-NOV      / 11:  29.07  28.76  26.29
16-DEC      / 12:  29.04  28.27  26.22


2. It also seems that the longitude axis of the data needs to be defined as positive values. I had a file where the longitude dimension was "degrees_east", but the values ranged from -180 to 180. The sampleXY function only worked after I regridded the data to positive values (i.e. -20 -> 340 etc), but it plotted fine. 

Cheers,

Paul