Seems to be related to the masked values: print r2010[:3,:3] [[-- -- --] [-- -- --] [-- -- --]]
print abs(r2010)[:3,:3] [[-- -- --] [-- -- --] [-- -- --]] print r2010[ r2010[:3,:3] <0 ] [-- -- -- -- -- -- -- -- --] print r2010[ abs(r2010)[:3,:3] < 0] [] Nicolas On 13 Mar 2014, at 16:52, Sudheer Joseph <[email protected]> wrote: > Dear experts, > I am encountering a strange behaviour of python data > array as below. I have been trying to use the data from a netcdf > file(attached herewith) to do certain calculation using below code. If I take > absolute value of the same array and look for values <.5 I get a different > value than the original array. But the fact is that this particular case do > not have any negative values in the array( but there are other files where it > can have negative values so the condition is put). I do not see any reason > for getting different numbers for values <.5 in case of bt and expected it to > be same as that of r2010. If any one has a guess on what is behind this > behaviour please help. > > > In [14]: from netCDF4 import Dataset as nc > > In [15]: nf=nc('r2010.nc') > In [16]: r2010=nf.variables['R2010'][:] > In [17]: bt=abs(r2010) > In [18]: bt[bt<=.5].shape > Out[18]: (2872,) > In [19]: r2010[r2010<.5].shape > Out[19]: (36738,) > > > bt.min() > Out[20]: 0.0027588337040836768 > > In [21]: bt.max() > Out[21]: 3.5078965479057089 > In [22]: r2010.max() > Out[22]: 3.5078965479057089 > In [23]: r2010.min() > Out[23]: 0.0027588337040836768 > > > > *************************************************************** > Sudheer Joseph > Indian National Centre for Ocean Information Services > Ministry of Earth Sciences, Govt. of India > POST BOX NO: 21, IDA Jeedeemetla P.O. > Via Pragathi Nagar,Kukatpally, Hyderabad; Pin:5000 55 > Tel:+91-40-23886047(O),Fax:+91-40-23895011(O), > Tel:+91-40-23044600(R),Tel:+91-40-9440832534(Mobile) > E-mail:[email protected];[email protected] > Web- http://oppamthadathil.tripod.com > ***************************************************************<r2010.nc>_______________________________________________ > NumPy-Discussion mailing list > [email protected] > http://mail.scipy.org/mailman/listinfo/numpy-discussion _______________________________________________ NumPy-Discussion mailing list [email protected] http://mail.scipy.org/mailman/listinfo/numpy-discussion
