PD подсчитывает, сколько элементов происходит в другом столбце
df['Counts'] = df.groupby(['Color'])['Value'].transform('count')
Hambo
df['Counts'] = df.groupby(['Color'])['Value'].transform('count')df['sex'].value_counts()
print df
col1 education
0 a 9th
1 b 9th
2 c 8th
print df.education == '9th'
0 True
1 True
2 False
Name: education, dtype: bool
print df[df.education == '9th']
col1 education
0 a 9th
1 b 9th
print df[df.education == '9th'].shape[0]
2
print len(df[df['education'] == '9th'])
2