[Numpy-discussion] Reading a big netcdf file
Wed Aug 3 11:50:50 CDT 2011
On 8/3/11 9:30 AM, Kiko wrote:
> I'm trying to read a big netcdf file (445 Mb) using netcdf4-python.
I've never noticed that netCDF4 was particularly slow for reading
(writing can be pretty slow some times). How slow is slow?
> The data are described as:
please post the results of:
ncdump -h the_file_name.nc
So we can see if there is anything odd in the structure (though I don't
know what it might be)
Post your code (in the simnd pplest form you can).
and post your timings and machine type
Is the file netcdf4 or 3 format? (the python lib will read either)
As a reference, reading that much data in from a raw file into a numpy
array takes 2.57 on my machine (a rather old Mac, but disks haven't
gotten much faster). YOu can test that like this:
a = np.zeros((21601, 10801), dtype=np.uint16)
timeit a = np.fromfile('temp.npa', dtype=np.uint16)
(using ipython's timeit)
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