count cases in a pandas code example

Example 1: count values pandas

>>> index = pd.Index([3, 1, 2, 3, 4, np.nan])
>>> index.value_counts()
3.0    2
4.0    1
2.0    1
1.0    1
dtype: int64

Example 2: pandas count values by column

df = pd.DataFrame({'a':list('abssbab')})
df.groupby('a').count()

Example 3: pandas count

>>> df.set_index(["Person", "Single"]).count(level="Person")
        Age
Person
John      2
Lewis     1
Myla      1

Example 4: count values python

from collections import Counter
values=np.ones(10)
Counter(values)