Re: [ferret_users] Reading text file and creating netcdf file by using define axis from variable

[Ansley Manke <ansley.b.manke@xxxxxxxx>]

Hi Don,
Defining an axis directly from the data only makes sense if the data is actually organized as a grid.

Your data looks like it's at a set of scattered points. Is that the case? To check what the distribution of the points looks like, you can plot them as marks on a map

   yes? file/skip=1/var="lat,lon,grd" Data.txt
   yes? go basemap
   yes? plot/vs lon, lat

If the points are scattered, you could use one of the SCAT2GRID functions. Define a grid,  and call the function to interpolate the variable GRD onto the grid.

--Ansley

On 5/31/2013 6:44 AM, Don DNA wrote:

Please anyone help me, I am having text file, I could able to read it using following command

yes? file/skip=1/var="lat,lon,grd" Data.txt
yes? sh d
     currently SET data sets:
    1> ./Data.txt  (default)
 name     title                             I         J         K         L         M         N
 LAT      LAT                              1:20480   ...       ...       ...       ...       ...
 LON      LON                              1:20480   ...       ...       ...       ...       ...
 GRD      GRD                              1:20480   ...       ...       ...       ...       ...


 list /i=1:10 lat,lon,grd
             DATA SET: ./Data.txt
             X: 0.5 to 10.5
 Column  1: LAT
 Column  2: LON
 Column  3: GRD
             LAT    LON    GRD
1    /  1:  11.83  88.93  0.3000
2    /  2:  11.95  87.95  0.1000
3    /  3:  12.10  86.98  0.3000
4    /  4:  17.67  40.43  0.3000
5    /  5:  24.82  57.92  0.3000
6    /  6:  13.28  42.93  0.0500
7    /  7:   7.93  73.32  0.1800
8    /  8:   7.25  72.00  0.2400
9    /  9:   4.33  67.43  0.0600
10   / 10:  24.07  57.59  0.0200


define axis/X/units=Degrees_East xaxis=lon[i=1:2791]
 **ERROR: improper grid or axis definition: data for DEFINE AXIS/FROM_VARIABLE is not monotonic at index 2

define axis/Y/units=Degrees_north yaxis=lat[i=1:2791]
 **ERROR: improper grid or axis definition: data for DEFINE AXIS/FROM_VARIABLE is not monotonic at index 6

Now I want to create netcdf file, I searched in user list and in ferret website, in that I found that axis can be defined by using variable, but in my case I am unable to define axis from variable, I don't have much idea about ferret programming, please those who know kindly help me, and please go through attachment.


- Dona Clara.