[Numpy-discussion] NetCDF4/numpy question
Howard
howard at renci.org
Fri Jan 27 16:58:05 EST 2012
Oh, one other thing I should mention:
I did the install of numpy yesterday and I also have 1.6.1
Howard
On 1/27/12 4:54 PM, Howard wrote:
> Hi Olivier
>
> I added this to the code:
>
> print "modelData:", type(modelData), modelData.shape, modelData.size
> print "dataMin:", type(dataMin)
>
> and got
>
> modelData: <class 'numpy.ma.core.MaskedArray'> (1767734,) 1767734
> dataMin: <type 'float'>
>
> What's funny is I tried the example from
>
> http://docs.scipy.org/doc/numpy-1.6.0/numpy-user.pdf
>
> and it works fine for me. Maybe 1.7 million is over some threshhold?
>
> Thanks
> Howard
>
> >>> myarr = np.ma.core.MaskedArray([1., 0., np.nan, 3.])
> >>> myarr[np.isnan(myarr)] = 30
> >>> myarr
> masked_array(data = [ 1. 0. 30. 3.],
> mask = False,
> fill_value = 1e+20)
>
>
> On 1/27/12 4:42 PM, Olivier Delalleau wrote:
>> What are the types and shapes of modelData and dataMin? (it works for
>> me with modelData a (3, 4) numpy array and dataMin a Python float,
>> with numpy 1.6.1)
>>
>> -=- Olivier
>>
>> 2012/1/27 Howard <howard at renci.org <mailto:howard at renci.org>>
>>
>> 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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>>
>>
>
>
> --
> 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
--
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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