[Numpy-discussion] NetCDF4/numpy question
Howard
howard at renci.org
Fri Jan 27 16:18:06 EST 2012
Hi all
I am a fairly recent convert to python and I have got a question that's
got me stumped. I hope this is the right mailing list: here goes :)
I am reading some time series data out of a netcdf file a single
timestep at a time. If the data is NaN, I want to reset it to the
minimum of the dataset over all timesteps (which I already know). The
data is in a variable of type numpy.ma.core.MaskedArray called modelData.
If I do this:
for i in range(len(modelData)):
if math.isnan(modelData[i]):
modelData[i] = dataMin
I get the effect I want, If I do this:
modelData[np.isnan(modelData)] = dataMin
it doesn't seem to be working. Of course I could just do the first one,
but len(modelData) is about 3.5 million, and it's taking about 20
seconds to run. This is happening inside of a rendering loop, so I'd
like it to be as fast as possible, and I thought the second one might be
faster, and maybe it is, but it doesn't seem to be working! :)
Any ideas would be much appreciated.
Thanks
Howard
--
Howard Lander <mailto:howard at renci.org>
Senior Research Software Developer
Renaissance Computing Institute (RENCI) <http://www.renci.org>
The University of North Carolina at Chapel Hill
Duke University
North Carolina State University
100 Europa Drive
Suite 540
Chapel Hill, NC 27517
919-445-9651
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