The Bottleneck package is a collection of fast NumPy array functions written in Cython:NumPy/SciPy median, nanmedian, nanmin, nanmax, nanmean, nanstd, nanargmin, nanargmaxFunctions nanvarMoving window move_nanmeanGroup by group_nanmeanLet\'s give it a try. Create a NumPy array:>>> import numpy as np>>> arr = np.array([1, 2, np.nan, 4, 5])Find the nanmean:>>> import bottleneck as bn>>> bn.nanmean(arr)3.0Moving window nanmean:>>> bn.move_nanmean(arr, window=2)array([ nan, 1.5, 2. , 4. , 4.5])Group nanmean:>>> label = [\'a\', \'a\', \'b\', \'b\', \'a\']>>> bn.group_nanmean(arr, label)(array([ 2.66666667, 4. ]), [\'a\', \'b\'])Complete documentation: http://pypi.python.org/pypi/Bottleneck/0.2.0Requirements: