In [1]:

    

import numpy as np


    

In [2]:

    

a = np.array([np.nan for _ in range(5)])
a


    

    
Out[2]:





array([ nan,  nan,  nan,  nan,  nan])

In [3]:

    

a.sum()


    

    
Out[3]:





nan

In [4]:

    

a.nansum()


    

    




---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-4-3e72f4331ad2> in <module>()
----> 1 a.nansum()

AttributeError: 'numpy.ndarray' object has no attribute 'nansum'

In [5]:

    

a.mean()


    

    
Out[5]:





nan

In [6]:

    

a.nanmean()


    

    




---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-6-b829d53aa1df> in <module>()
----> 1 a.nanmean()

AttributeError: 'numpy.ndarray' object has no attribute 'nanmean'

In [7]:

    

np.nanmean(a)


    

    




/home/jep/anaconda3/envs/jupy/lib/python3.6/site-packages/ipykernel/__main__.py:1: RuntimeWarning: Mean of empty slice
  if __name__ == '__main__':






    
Out[7]:





nan

In [8]:

    

np.nansum(a)


    

    
Out[8]:





0.0

In [9]:

    

b = a.copy()
b[1] = 15.
b[3] = 5.
b is a, a, b


    

    
Out[9]:





(False,
 array([ nan,  nan,  nan,  nan,  nan]),
 array([ nan,  15.,  nan,   5.,  nan]))

In [10]:

    

np.nanmean(b), np.nansum(b)


    

    
Out[10]:





(10.0, 20.0)