Re: Missing values

["Mark A. Verschell" <verschel@xxxxxxxxxxxxxxxxxxxxx>]

On Oct 27, 10:30am, shenoi@csnio.ren.NIC.IN wrote:
> I came across a strange problem when I used the 'IF' condition to pick the
> zonal and meridional components of a vector based on the number of
> observations available in a grid.  In one case the vector has a zero value
> for one component (ie. v=0.0). In this case when I used the 'IF' condition,
> it reports v as missing rather than 0.0. The following will explain the
> problem better (see the values reported for 16-Sep, column 2 & 5).
>
> Is there any way out for this problem? I want 0.0 when the values are zeros.
> Not as 'missing value'. When I compute the annual mean (using @ave)
> I get umean with 12 values and vmean with 11 values rather than 12 values
> which is incorrect.
>-- End of excerpt from shenoi@csnio.ren.NIC.IN

Satheesh-

I am not certain exactly what is going on here, I tried to replicate it by
copying your data and definitions, but I got 0.00 for V1 on 16-SEP.

This indicates to me that somewhere in the chain of variable definitions you
are including something that IS undefined. I would suggest tracking this down
by looking specifically at the V1 for 16-SEP, and then looking at all the V
values that go into that - maybe one of the is undefined. I have appended my
version of your data, and the .jnl file I used in hopes that it will help.

-Mark

sh.dat
------
  -13.0 -13.00  20.00
  -61.0  -3.00  33.00
    7.0   6.00  34.00
  106.0 -13.00  24.00
  146.0 -22.00  66.00
   60.0 -18.00  51.00
   11.0 -17.00  67.00
   48.0 -18.00  48.00
   67.0   0.00  42.00
   83.0  32.00  36.00
  150.0 -10.00  40.00
   62.0  -2.00  53.00


sh.jnl
------
define axis/t="16-jan":"16-dec"/np=12 tsh
define grid/t=tsh gsh
file/var=u,v,nobs/grid=gsh sh.dat
let u1 = IF(NOBS GT 10) THEN U
let v1 = IF(NOBS GT 10) THEN V
let nobs1 = IF(NOBS GT 10) THEN NOBS
list/l=1:12 u,v,nobs,u1,v1,nobs

The output of the list is:
--------------------------
             DATA SET: ./sh.dat
             TIME: 01-JAN      00:00:05 to 31-DEC      05:2
 Column  1: U
 Column  2: V
 Column  3: NOBS
 Column  4: U1 is IF(NOBS GT 10) THEN U
 Column  5: V1 is IF(NOBS GT 10) THEN V
 Column  6: NOBS
                      U      V   NOBS     U1     V1   NOBS
16-JAN      /  1:  -13.0 -13.00  20.00  -13.0 -13.00  20.00
15-FEB      /  2:  -61.0  -3.00  33.00  -61.0  -3.00  33.00
16-MAR      /  3:    7.0   6.00  34.00    7.0   6.00  34.00
16-APR      /  4:  106.0 -13.00  24.00  106.0 -13.00  24.00
16-MAY      /  5:  146.0 -22.00  66.00  146.0 -22.00  66.00
16-JUN      /  6:   60.0 -18.00  51.00   60.0 -18.00  51.00
16-JUL      /  7:   11.0 -17.00  67.00   11.0 -17.00  67.00
16-AUG      /  8:   48.0 -18.00  48.00   48.0 -18.00  48.00
15-SEP      /  9:   67.0   0.00  42.00   67.0   0.00  42.00
16-OCT      / 10:   83.0  32.00  36.00   83.0  32.00  36.00
15-NOV      / 11:  150.0 -10.00  40.00  150.0 -10.00  40.00
16-DEC      / 12:   62.0  -2.00  53.00   62.0  -2.00  53.00

-- 
 Mark Verschell                     NASA/Goddard Space Flight Center
 verschell@neptune.gsfc.nasa.gov    Code 970/Lab. for Hydrospheric Proc.
 301-286-2027  Fax: 301-286-1761    Greenbelt, MD 20771