[gradsusr] fwrite data conversion

mehwish ramzan mehwish.ramzan at gmail.com
Sat Aug 23 07:30:27 EDT 2014


Dear GrADS users,

I need your kind help in solving this issue.
I converted my model outputs from hourly data to daily data using fwrite
command as follows;

'open r_p.ctl'
'set x 1 257'
'set y 1 170'
'set lev 1'
t1=1
while(t1<=360)
'set t ' t1
'set fwrite pre.dat'
'set gxout fwrite'
'd ave(pratesfc,t='t1',t='t1+23')'
'disable fwrite'
t1= t1+24
endwhile

Now in order to display the binary data i prepared following control file;

dset ^pre.dat
options little_endian
title sample daily data
undef 9.999e+20
xdef 257 linear 7.756   0.47019140625
ydef 170 linear -20.826 0.47019140625
zdef   1  levels  1
tdef 360 linear 00z01jan1999 1dy
*
vars 1
pratesfc 0 99 surface precipitation
endvars

When i opened this control file in grads  (v1.9.0-rc1 32-bit little-endian
readline sdf/xdf netcdf lats athena printim), it successfully displays
first time step, but from second time step on-wards, it give following
error message;

ga-> open prect.ctl
Scanning description file:  prect.ctl
Data file pre.dat is open as file 1
LON set to 7.756 128.125
LAT set to -20.826 58.6363
LEV set to 1 1
Time values set: 1999:1:1:0 1999:1:1:0
ga-> set t 2
Time values set: 1999:1:2:0 1999:1:2:0
ga-> d pratesfc
Low Level I/O Error:  Read error on data file
  Data file name = pre.dat
  Error reading 257 bytes at location 43690
Data Request Error:  Error for variable 'pratesfc'
  Error ocurred at column 1
DISPLAY error:  Invalid expression
  Expression = pratesfc


The original hourly data file was of size= 6903 (with 87 variables)  ,
while the file i prepared for reading (one variable)  as daily data is of
size= 258, while my working platform is Linux.

This is first time i am using fwrite function.Please guide me where i am
doing wrong.

Thank You

With Best Regards,

Mehwish
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