[R-sig-Geo] problem reading netcdf file with readGDAL: "no bands in dataset"

[ElenaC]

Thanks a lot, Mike! 
I have finally managed to select the subdataset, and everything is working
now! 

Cheers,
Elena



Michael Sumner-2 wrote:
> 
> See this page for more information about the GDAL approach to NetCDF:
> http://www.gdal.org/frmt_netcdf.html
> 
> If you can construct the subdataset name correctly then readGDAL
> should be able to return the given variable, as a single band
> SpatialGridDataFrame.
> 
> 
> 
> On Thu, Nov 26, 2009 at 7:27 AM, Michael Sumner <mdsumner at gmail.com>
> wrote:
>> There are a number of reasons why GDAL might not be able to read data
>> from NetCDF, although it might appear to get some metadata upfront.
>> The 512x512 thing is a default, and to me means that there are
>> multiple variables in the file, and GDAL requires direct reference to
>> only one of them as a "subdataset". The syntax is something like this:
>>
>> NETCDF:"/path/to/filename.nc":varname
>>
>> If you use gdalinfo at the command line it will tell you the
>> subdataset strings you can use - the rgdal bindings don't reconstruct
>> the output that that utility gives you.
>>
>> Cheers, Mike.
>>
>> On Thu, Nov 26, 2009 at 12:34 AM, ElenaC <E.Couce.07 at bristol.ac.uk>
>> wrote:
>>>
>>> Hi all,
>>>
>>> I'm trying to open a netcdf file using the rgdal library, but readGDAL
>>> and
>>> GDALinfo don't seem to be able to correctly access the information in
>>> the
>>> file. It is probably a stupid mistake because I don't understand what
>>> I'm
>>> doing, but I have already spent a long time trying to sort it out and I
>>> could really use some help with it.
>>>
>>> When I try readGDAL, it fails with the error that there are "no bands in
>>> dataset". This is the output I get from GDALinfo:
>>>
>>>> GDALinfo(fname)
>>> rows        512
>>> columns     512
>>> bands       0
>>> origin.x        0
>>> origin.y        1
>>> res.x       1
>>> res.y       1
>>> oblique.x   0
>>> oblique.y   0
>>> driver      netCDF
>>> projection  NA
>>>
>>> Warning messages:
>>> 1: In dim(x) : no bands in dataset
>>> 2: In GDALinfo(fname) : no bands in dataset
>>>
>>>
>>>
>>> But from opening the file with Panoply, it seems it actually contains
>>> four
>>> variables, two of them 360*180 matrices with the geographical info I'm
>>> trying to access (global data with 1 degree spatial resolution), and the
>>> two
>>> others called "lat" and "lon" with the latitude and longitude values.
>>>
>>> I don't understand why GDALinfo is telling me that the file has 512 rows
>>> and
>>> 512 columns and that there are "no bands". What can I do to access the
>>> variables I want?
>>>
>>> Any help would be greatly appreciated!
>>> Elena
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>>>
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>>
> 
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