Just curious, why can't it be done in the manner that I thought it could be
done?
Why do I have to go install a whole other software to do what should be pretty
simple?
I need to do work, not install software...
I might as well just do it my own made up wonky way that works...
seem like every bag of worms just contains another bag of worms...
frustrating!
----- Original Message -----
From: "Signell, Richard" <rsignell@xxxxxxxx>
Date: Monday, November 19, 2012 3:36 pm
Subject: Re: [netcdfgroup] Extracting time series from netCDF file
To: Jose Borrero <jborrero@xxxxxxx>
Cc: netcdfgroup@xxxxxxxxxxxxxxxx
> Jose,
> If you were used to using Matlab but no longer have it, you might try
> Python, which you can use in a similar fashion. This example shows how
> to extract and plot a time series of wave heights from a remote
> OPeNDAP dataset, but would work the same with a local NetCDF file:
> http://nbviewer.ipython.org/4113653/
>
> This code uses the NetCDF4-Python module, which reads NetCDF and
> OPeNDAP datasets using the same syntax. It can be a pain to install,
> but I didn't have to build it because I have the Enthought Python
> Distribution, which includes NetCDF4-Python with OPeNDAP support. (I
> think the full version of the EPD is free for folks with .edu
> addressses, and of course there are many other options for free
> scientific distributions as well).
>
> Good luck,
> -Rich
>
>
> On Mon, Nov 19, 2012 at 12:59 PM, Jose Borrero <jborrero@xxxxxxx>
> wrote:>
> >
> > Hi All,
> >
> > I have a program that produces netCDF files of water levels over
> a geographic region fro different times.
> >
> > the header looks like this:
> >
> > ===============================================
> > lon = 720 ;
> > lat = 330 ;
> > grid_lon = 720 ;
> > grid_lat = 330 ;
> > rows = 3 ;
> > clms = 3 ;
> > time = UNLIMITED ; // (226 currently)
> > variables:
> > double lon(lon) ;
> > lon:long_name = "longitude" ;
> > lon:units = "degrees_east" ;
> > lon:point_spacing = "even" ;
> > double lat(lat) ;
> > lat:long_name = "latitude" ;
> > lat:units = "degrees_north" ;
> > lat:point_spacing = "uneven" ;
> > double grid_lon(grid_lon) ;
> > grid_lon:long_name = "longitude" ;
> > grid_lon:units = "degrees_east" ;
> > grid_lon:point_spacing = "even" ;
> > double grid_lat(grid_lat) ;
> > grid_lat:long_name = "latitude" ;
> > grid_lat:units = "degrees_north" ;
> > grid_lat:point_spacing = "uneven" ;
> > double O2Geo(clms, rows) ;
> > O2Geo:long_name = "rotation matrix" ;
> > float max_amp(grid_lat, grid_lon) ;
> > max_amp:long_name = "Maximum Wave Amplitude" ;
> > max_amp:units = "centimeters" ;
> > max_amp:_FillValue = -1.e+34f ;
> > max_amp:missing_value = -1.e+34f ;
> > double time(time) ;
> > time:long_name = "time" ;
> > time:units = "seconds" ;
> > time:calendar = "gregorian" ;
> > float ha(time, lat, lon) ;
> > ha:long_name = "Wave Amplitude" ;
> > ha:units = "centimeters" ;
> > ha:missing_value = -1.e+34f ;
> > ha:_FillValue = -1.e+34f ;
> > ===============================================
> >
> > i would like to extract a time series of data at a specific
> location.>
> > I have been looking at the ncdump command and thinking there
> would be a way do it at the command line, i.e. something like:
> >
> > ncdump -v ha(lat,lon, time[1=>t]) datafile.nc > timeseries.cdl
> >
> > (I realize the syntax is totally wrong, i am just trying to
> express how I would specify a lat/lon and ask for the data over the
> entire time)
> >
> > then using ncgen to make a new binary netCDF that can be read by
> GMT's nc2xy and output a simple 2 column time series.
> >
> > but I don't think I can specify things that way with ncdump.
> >
> > I then looked in to using the ncBrowse software. I have managed
> to use that to specify a time series of data at a point, and even
> write that data out to a CDL file. However, the file generated by
> ncBrowse (pasted below in an edited form) cannot be read by nc2xy
> and has characters that are not compatible with ncgen
> >
> > nc2xy tells me: nc2xy: NetCDF: Unknown file format [ha.cdl]
> >
> > and ncgen tells me:
> >
> > ncgen: ha.cdl line 7: syntax error, unexpected '=', expecting ','
> or ')'
> >
> > ===================================================
> > netcdf ha.cdl {
> > dimensions:
> > time = UNLIMITED ; // (226 currently)
> > lat = 1 ;
> > lon = 1 ;
> > variables:
> > double time(time=226);
> > time:long_name = "time";
> > time:units = "seconds";
> > time:calendar = "gregorian";
> > double lat(lat=330);
> > lat:long_name = "latitude";
> > lat:units = "degrees_north";
> > lat:point_spacing = "uneven";
> > double lon(lon=720);
> > lon:long_name = "longitude";
> > lon:units = "degrees_east";
> > lon:point_spacing = "even";
> > float ha(time=226, lat=330, lon=720);
> > ha:long_name = "Wave Amplitude";
> > ha:units = "centimeters";
> > ha:missing_value = -1.0E34f; // float
> > ha:_FillValue = -1.0E34f; // float
> > data:
> >
> > time = 0.0, <ALL THE TIMES>, 14400.0 ;
> >
> > lat = 24.00833 ;
> >
> > lon = 60.00833 ;
> >
> > ha = 1.0723767, <ALL THE ha VALUES>1.6242466 ;
> >
> > }
> > ===================================================
> >
> > so then, I go in to the ha.cdl file and edit the header in a text
> editor to remove the =226, =330 and =720 bits and change the line:
> >
> > float ha(time=226, lat=330, lon=720);
> >
> > to
> >
> > float ha(time);
> >
> > I then run run:
> >
> > ncgen -b -o ha.nc ha.cdl
> >
> > and make a file ha.nc which then can be accessed by nc2xy through
> the command:
> >
> > nc2xy ha.nc -Ftime/ha > ha.txt
> >
> > to create the file ha.txt which looks like:
> >
> > ===========================
> > 0.000 17.423
> > 64.000 61.289
> > 128.000 36.575
> > <...SNIP...>
> > 14336.000 -2.210
> > 14400.000 -2.147
> > ===========================
> >
> > and is exactly what i want! Two columns, time and ha at that
> particular lat/lon So I know it is possible...
> >
> > So, if you are still with me, how can i do this more simply,
> through the command line preferably, or even a small script that goes:
> >
> > ncdump (args)
> > ncgen (args)
> > nc2xy (args)
> >
> > would be fine, but I just need to know the right arguments to
> make it all talk to each other.
> >
> > if you can help me, MANY, MANY, THANKS!!!!
> >
> > -jose
> >
> > (p.s. i used to do this with MATLAB, but I recently had my
> computer with MATLAB die, and i can't get it up and running again,
> so i am trying to do this an alternative way...)
> >
> >
> > _______________________________________________
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> > netcdfgroup@xxxxxxxxxxxxxxxx
> > For list information or to unsubscribe, visit:
> http://www.unidata.ucar.edu/mailing_lists/
>
>
> --
> Dr. Richard P. Signell (508) 457-2229
> USGS, 384 Woods Hole Rd.
> Woods Hole, MA 02543-1598
>
