for your particular case: >>> a = np.array([1, 5, 4, 99], 'f') >>> b = np.array([3, 7, 2, 8], 'f') >>> c = b.copy() >>> d = a!=99 >>> c[d] = (a[d] + b[d])/2. >>> c array([ 2., 6., 3., 8.], dtype=float32) >>>
On Tue, Jul 14, 2009 at 3:36 PM, Chris Colbert<sccolb...@gmail.com> wrote: > index with a boolean array? > >>>> import numpy as np >>>> a = np.array([3, 3, 3, 4, 4, 4]) >>>> a > array([3, 3, 3, 4, 4, 4]) >>>> np.average(a) > 3.5 >>>> b = a != 3 >>>> b > array([False, False, False, True, True, True], dtype=bool) >>>> np.average(a[b]) > 4.0 >>>> > > > On Tue, Jul 14, 2009 at 3:33 PM, Greg Fiske<gfi...@whrc.org> wrote: >> Dear list, >> >> >> >> I’m learning to work with numpy arrays. Can somebody explain how to get the >> average of two separate arrays while ignoring a user defined value in one >> array? >> >> >> >> For example: >> >>>>>a = numpy.array([1,5,4,99]) >> >>>>>b = numpy.array([3,7,2,8]) >> >> >> >> Ignoring the value 99, the result should be an array like c= ([2,6,3,8]) >> >> >> >> Thanks for any advice, >> >> >> >> Greg >> >> >> >> >> >> Greg Fiske >> >> Research Associate/GIS Manager >> >> The Woods Hole Research Center >> >> 149 Woods Hole Road >> >> Falmouth MA, 02540 >> >> 508-540-9900x139 >> >> gfi...@whrc.org >> >> http://whrc.org >> >> >> >> _______________________________________________ >> NumPy-Discussion mailing list >> NumPy-Discussion@scipy.org >> http://mail.scipy.org/mailman/listinfo/numpy-discussion >> >> > _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
