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Re: ASCCII, [Fwd: Lessons about scatter2grid*, ie gridding point data]
Hi Guille,
seems you ran into similar problems Lev had a while ago -
I have appended her mail below.
>From that, I figure, you should try:
DEFINE AXIS/x=1:ndata:1 ndat ! ndata no of data points
define grid/x=ndat gin
FILE/VAR="long,lat,data" /GRID=gin sourcemodif.txt
gridata=
scatter2gridgauss_xy(long,lat,data,x[gx=40:50:5],y[gy=70:80:5],2.)
I did not test it, though...
Your approach:
yes? DEFINE AXIS/X=40:50:5 xlong
yes? DEFINE AXIS/Y=70:80:5 ylat
yes? DEFINE GRID/X=xlong/Y=ylat gridata
yes? FILE/VAR="long,lat,data"/GRID=gridata sourcemodif.txt
ran into trouble in this line already, because here you tell ferret,
that all the variables, long,lat,data, are on the 2-d grid griddata and
ferret will expect to read them in an appropriate order from the file.
yes? LET gridata= scatter2gridgauss_xy(long,lat,data,xlong,ylat,2.)
yes? CONTOUR gridata
**ERROR: variable unknown or not in data set: YLAT
ylat is only the name of the new axis you like to use and not a variable
for ferret.
The original grid your data are on is just one linear axis, as Lev
points
out below.
For the terms x[gx=40:50:5],y[gy=70:80:5] have a look at the sections
about regridding and dynamic axes in the user guide.
http://ferret.wrc.noaa.gov/Ferret/Documentation/Users_Guide/v50/index.html
Good luck,
Joerg
Lev Tarasoff wrote:
>
> A clarification for those gridding point data with scatter2grid*: make
> sure that your input data is in array (and not matrix) form. The function
> will not reshape matrices into arrays (and the gridding messes up). So to
> grid a set (array, or matrix) of point data, use the following general
> approach:
>
> yes? define axis/x=1:(number of points):1 x1
> yes? define grid/x=x1 gin
> yes? FILE/VAR="xlong,ylat,data" /GRID=gin my_input_data_file
> !also ensure that longitude is >0. Ferret generally doesn't like
> longitude<0
>
> yes? Let gridded_data= scatter2gridgauss_xy(xlong,ylat,data,
> x[gx=new_xaxis], y[gy=new_yaxis], cutoff_parameter)
> !smaller cutoff_parameter => less smoothing
>
> Also, I've run into memory(?) problems with scatter2gridlaplace_xy
> when gridding a large number of points (at least on RH linux
> 6.0). However, scatter2gridgauss_xy has been quite stable for me.
>
> cheers
>
> Lev Tarasoff - Dept of Physics, University of Toronto,
> 60 St. George St., Toronto, Ontario, CANADA, M5S 1A7
> Tel (416)-946-3019 Fax (416)-978-8905
> email: lev@atmosp.physics.utoronto.ca
--
Jörg Kaduk Tel.: 1 650 325 1521 x 416
Carnegie Institution of Washington FAX: 1 650 325 6857
Dept. of Plant Biology
260 Panama Street joerg@jasper.stanford.edu
Stanford, CA 94305-1297 http://Jasper.Stanford.EDU/joerg/
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