What is the difference between size and count in pandas?

That is the difference between groupby("x").count and groupby("x").size in pandas ?

Does size just exclude nil ?

size includes NaN values, count does not:

    In [46]:
    df = pd.DataFrame({'a':[0,0,1,2,2,2], 'b':[1,2,3,4,np.NaN,4], 'c':np.random.randn(6)})
    df

    Out[46]:
       a   b         c
    0  0   1  1.067627
    1  0   2  0.554691
    2  1   3  0.458084
    3  2   4  0.426635
    4  2 NaN -2.238091
    5  2   4  1.256943

    In [48]:
    print(df.groupby(['a'])['b'].count())
    print(df.groupby(['a'])['b'].size())

    a
    0    2
    1    1
    2    2
    Name: b, dtype: int64

    a
    0    2
    1    1
    2    3
    dtype: int64

From: stackoverflow.com/q/33346591