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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...) > > > > > > _______________________________________________ > > netcdfgroup mailing list > > 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 >
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