Due to the current gap in continued funding from the U.S. National Science Foundation (NSF), the NSF Unidata Program Center has temporarily paused most operations. See NSF Unidata Pause in Most Operations for details.
Due to the current gap in continued funding from the U.S. National Science Foundation (NSF), the NSF Unidata Program Center has temporarily paused most operations. See NSF Unidata Pause in Most Operations for details.
Matt, > I was able to write a simple copy program using the netCDF (v1) Java library. > > However, I would like to know if there is some way of reading > multidimensional > variables (like time,X,Y,Z) out of one netCDF file, writing them directly to > a new netCDF file. Do you know if there is some high performance way of > doing this in either version 1 or 2 of the netCDF Java library? Currently, I > > am using toArray() to read the data from the source file and it puts it in > a 1d array. I am having to convert the 1d array to a multidimensional array > then use ArrayMultiArray to copyin() the data. This process is very time > consuming. Do know of some way where I could take the data in as a 1d > array, then write it out using the 1d array? A really high-performance variable copy method would just copy the bytes from the source file to the destination file, without bothering to decode from XDR to native representation and then encode again before writing to disk. This would violate all the encapsulation, but might be an appropriate optimization to do inside the package where the details of the disk representation are known. For non-record variables, it would just copy a single block of contiguous bytes, whereas for a record variable, it would need to do one copy for each record. However, no methods exist currently in either version 1 or 2 to do this. In version 1, I'm afraid I don't know of any way to avoid the inefficiency you are encountering. I had thought the copyin() method could take values from a 1D array, but it looks like that isn't the case. However, there's a reply to a support message dealing with a very similar problem in version 1 that might give you a lead on how to avoid the inefficiency you are seeing, if you want to continue to use the version 1 interface. http://www.unidata.ucar.edu/projects/coohl/mhonarc/MailArchives/netcdf/msg02956.html I believe it's possible to do what you want more efficiently in version 2, and am CC:ing John Caron for further advice on this. Version 2 at least has a reshape() method in ucar.ma2.Array that makes it easy to change the shape of an array. --Russ
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