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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
Martin Dix <martin.dix@xxxxxxxxxxxx> wrote: > For simplicity call the unlimited dimension t. A netcdf file stores > all the data for t=1, then for t=2 etc. Your description of the > array indices means that each subarray is scattered through the > entire file and requires accessing almost every file block. Things > should be a lot better if you write subarrays of 8000 x 3 x 1 or if > you can't do this, rearrange the file so that the 8000 dimension is > unlimited rather than the 16000 dimension. But I must read along both major dimensions, depending on the type of analysis I am doing. From your explanation it seems that one the two access types will always be very slow. Shouldn't it be possible for the netCDF library to organize the data in such a way that a scan along any dimension is doable with acceptable efficiency? For example, each contiguous file block could correspond to a subarray of approximately equal extent along each dimension. Could I gain anything from not using an unlimited dimension? In some cases I know the final size before creating the file, and in others it might be worth to make a fixed-size copy before some lengthy analysis. -- ------------------------------------------------------------------------------- Konrad Hinsen | E-Mail: hinsen@xxxxxxxxxxxxxxx Centre de Biophysique Moleculaire (CNRS) | Tel.: +33-2.38.25.55.69 Rue Charles Sadron | Fax: +33-2.38.63.15.17 45071 Orleans Cedex 2 | Deutsch/Esperanto/English/ France | Nederlands/Francais -------------------------------------------------------------------------------
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