Group by and take count of first occurrence Pandas Dataframe

Question

A pandas dataframe has 2 columns.

Number	Character
111	a
111	a
111	b
111	b
111	c
222	b
222	a
222	c
222	b
222	a
222	c
333	c
333	a
333	a
333	b
333	c
333	c

Answer 1

first filter only first values by GroupBy.transform and GroupBy.first comparing by original values in boolean indexing and then count values by GroupBy.size:

df = df[df.groupby('Number')['Character'].transform('first').eq(df['Character'])]

df = df.groupby(['Number','Character']).size().reset_index(name='count')
print (df)    
   Number Character  count
0     111         a      2
1     222         b      2
2     333         c      3