import numpy as np
import pandas as pd
s = pd.Series([1, 1, 2, 1, 2, 2, 2, 1, 1, 3, 3, 4, 5, 5, 7, np.NaN])
s
len(s)
s.size
s.shape
s.unique()
s.count()
s.mean()
s.value_counts()
a = np.array([2, 2, 2, np.NaN])
print(a.mean())
b= pd.Series(a)
print(b.mean())
s.head(3)
s.tail(2)