value in dataframe column number of times reappear code example

Example 1: pd count how many item occurs in another column

df['Counts'] = df.groupby(['Color'])['Value'].transform('count')

Example 2: pandas count occurrences of certain value in row

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