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Hi all, Thanks for the earlier replies. I was looking at the OPeNDAP Server Dataset Access Form (http://test.opendap.org/opendap/data/nc/sst.mnmean.nc.gz.html) and under Action, there's a "Get as NetCDF" option in this form, however the Thredds instance I have deployed do not have this option. Under the General Help it reads: To get data in ASCII, various common formats or DODS binary objects, click on one of the buttons labeled Get .... The Get ASCII and Get DODS Data Object buttons will always be present. Other buttons may be present providing access other types of return formats such as NetCDF, HDF, et cetera. Note that in order to use the DODS Data Objects, you'll need to download software from the OPeNDAP web site to decode them. How do I go about enabling this option? I am interested in being able to download the subsetted datasets as Netcdf files. Thank you for your time. Regards, Derrick Wong Software Engineer | ASRDC (Australian Spatial Research Data Commons) Project | CSIRO Phone: +61 8 6436 8945 derrick.wong@xxxxxxxx | www.csiro.au Address: ARRC (Australian Resources Research Centre), 26 Dick Perry Avenue, Kensington WA 6151, Australia -----Original Message----- From: Roy Mendelssohn [mailto:Roy.Mendelssohn@xxxxxxxx] Sent: Wednesday, 21 July 2010 10:37 PM To: Wong, Derrick (CESRE, Kensington) Cc: thredds@xxxxxxxxxxxxxxxx Subject: Re: [thredds] Thredds Opendap request Relational constraint expressions do no work for grids in OpeNDAP. You have to constrain based on the range of indices in the grid. If you go to the OPeNDAP html page it will help guide you to perform a subset. For example from one of the datasets my group serves: http://oceanwatch.pfeg.noaa.gov/thredds/dodsC/satellite/BA/ssta/mday.html to get the first time period, the first 30 lats and 50 lons the constraitn would be: http://oceanwatch.pfeg.noaa.gov/thredds/dodsC/satellite/BA/ssta/mday?BAssta[0:1:0][0:1:0][0:1:29][0:1:49] HTH, -Roy On Jul 21, 2010, at 12:01 AM, Derrick.Wong@xxxxxxxx wrote: > Hi all, > > I have set up a TDS (Version 4.1.20100520.1554 - 20100520.1554) and I am > having some problem requesting for data using the built-in OPeNDAP service. > > I am trying to subset the dataset based on a spatial extent (bbox), and in > the opendap documentation, it is mentioned that this is possible if you > specify a constraint in your request. > (http://opendap.org/user/guide-html/guide_34.html#id6) > > I am getting the following error when I try to make a simple query > http://apacsrv6/thredds/dodsC/bom/mslp.2009043000.nc.ascii?mslp&lat>15.0 : > > Error { > code = 2; > message = "The variable `15' was not found in the dataset."; > }; > > > > My Dataset is as follows: > > Dataset { > Float32 lat[lat = 480]; > Float32 lon[lon = 600]; > Int32 tm_step_size; > Int32 base_date; > Int32 base_time; > Int32 valid_date[time = 1]; > Int32 valid_time[time = 1]; > String seg_type[time = 1]; > Float32 mslp[time = 1][lat = 480][lon = 600]; > } bom/mslp.2009043000.nc; > --------------------------------------------- > lat[480] > -55.0, -54.875, -54.75, -54.625, ....... > > lon[600] > 95.0, 95.125, 95.25, 95.375, 95.5, ...... > > tm_step_size, 240 > base_date, 20090430 > base_time, 0 > valid_date[1] > 20090430 > > valid_time[1] > 0 > > seg_type[1] > "FORC" > > mslp[1][480][600] > > [0][0], 983.6426, 983.6654, 983.6847, 983.7006, .... > [0][1], .... > ..... > > > > I have noted that the syntax of the OPeNDAP request within thredds is a bit > different, could someone kindly assist? > > Thank you for your time. > > Regards, > > > Derrick Wong > Software Engineer | ASRDC (Australian Spatial Research Data Commons) Project > | CSIRO > > Phone: +61 8 6436 8945 > derrick.wong@xxxxxxxx | www.csiro.au > Address: ARRC (Australian Resources Research Centre), 26 Dick Perry Avenue, > Kensington WA 6151, Australia > > PLEASE NOTE > The information contained in this email may be confidential or privileged. > Any unauthorised use or disclosure is prohibited. If you have received this > email in error, please delete it immediately and notify the sender by return > email. Thank you. To the extent permitted by law, CSIRO does not represent, > warrant and/or guarantee that the integrity of this communication has been > maintained or that the communication is free of errors, virus, interception > or interference. > Please consider the environment before printing this email. > > > > _______________________________________________ > thredds mailing list > thredds@xxxxxxxxxxxxxxxx > For list information or to unsubscribe, visit: > http://www.unidata.ucar.edu/mailing_lists/ ********************** "The contents of this message do not reflect any position of the U.S. Government or NOAA." ********************** Roy Mendelssohn Supervisory Operations Research Analyst NOAA/NMFS Environmental Research Division Southwest Fisheries Science Center 1352 Lighthouse Avenue Pacific Grove, CA 93950-2097 e-mail: Roy.Mendelssohn@xxxxxxxx (Note new e-mail address) voice: (831)-648-9029 fax: (831)-648-8440 www: http://www.pfeg.noaa.gov/ "Old age and treachery will overcome youth and skill." "From those who have been given much, much will be expected" -----Original Message----- From: Daniel Holloway [mailto:d.holloway@xxxxxxxxxxx] Sent: Wednesday, 21 July 2010 9:59 PM To: Wong, Derrick (CESRE, Kensington) Cc: thredds@xxxxxxxxxxxxxxxx; support@xxxxxxxxxxx support Subject: Re: [thredds] Thredds Opendap request Derrick, The documentation you're referencing shows how to make constraint expressions to both 'sequence' containers, and 'arrays and grids'. The selection operation you're using is only applicable to 'sequences' and not 'arrays and grids' (at least not currently though value-based array selection is often a requested capability for the DAP). To accomplish your goal you would need to retrieve the 'lat' variable first to determine the indices in the value range you're looking for (.i.e., lat > 15) then you could constrain the 'mslp' variable accordingly, like so: http://www.apacsrv6/thredds/dodsC/bom/mslp.2009043000.nc.asc? mslp[0][355:479][0:599] the above assumes that 'lat' values greater than '15' reside in the indices [355 to 479] (the top of the lat dimension), and you want all the 'lon' coverage. Dan
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