[ferret_users] Reading an ascii file: longitute latitute variable

[AV Gallego-Sala <Angela.Gallego-Sala@xxxxxxxxxxxxx>]

Dear Ferret Users,

I am new to Ferret and would be very grateful if somebody could help me
with a "simple" problem. I am using FERRET v5.70 (alpha) on a Mac OS X
10.5.6 and I don't seem to be able to read a simple ascii file of the
following kind:

  -53.500000       68.500000      0.99750608
  -53.000000       68.500000      0.99756086
  -52.500000       68.500000      0.99761266
  -52.000000       68.500000      0.99761307
  -51.500000       68.500000      0.99767214
  -51.000000       68.500000      0.99771249
  -50.500000       68.500000       0.0000000

where the first column is the longitude, the second is the latitude and
the last is the variable (dryness index).

I tried:

FILE/VAR=xpoints,ypoints,dry filename
DEFINE AXIS/from_data/X/name=xaxis/UNITS=degrees xpoints
 **ERROR: improper grid or axis definition: data for DEFINE
AXIS/FROM_VARIABLE is not monotonic

I then thought perhaps the longitude needs to be sorted monotonically, so
I changed the file so that the longitude increased all the time, this
worked for the x axis, but still got the same error for the y axis (which
of course is not monotonic now):

FILE/VAR=xpoints,ypoints,dry filename
yes? DEFINE AXIS/from_data/X/name=xaxis/UNITS=degrees xpoints
 *** NOTE: Axis has repeated values -- micro-adjusting ...
yes? DEFINE AXIS/from_data/Y/name=yaxis/UNITS=degrees ypoints
 **ERROR: improper grid or axis definition: data for DEFINE
AXIS/FROM_VARIABLE is not monotonic

Anybody has any suggestions? I will so very, very grateful!

Cheers,
Angela
-- 
AV Gallego-Sala
QUEST
 Department of Earth Sciences
 University of Bristol
 12 Berkeley Square
 BS8 1HB

Tel. +44 (0) 117 3314462
Fax. +44 (0) 117 3314124

Angela.Gallego-Sala@xxxxxxxxxxxxx