access column by index pandas code example

Example 1: select rows from dataframe pandas

from pandas import DataFrame

boxes = {'Color': ['Green','Green','Green','Blue','Blue','Red','Red','Red'],
         'Shape': ['Rectangle','Rectangle','Square','Rectangle','Square','Square','Square','Rectangle'],
         'Price': [10,15,5,5,10,15,15,5]
        }

df = DataFrame(boxes, columns= ['Color','Shape','Price'])

select_color = df.loc[df['Color'] == 'Green']
print (select_color)

Example 2: get column index pandas

df = pd.read_csv('thanksgiving_w_age_income.csv')

# Obtain Column Indices:
gravy = df.columns.get_loc("Do you typically have gravy?")
meet_friends = df.columns.get_loc('Have you ever tried to meet up with hometown friends on Thanksgiving night?')
friendsgiving = df.columns.get_loc('Have you ever attended a "Friendsgiving?"')

Example 3: add an index column in range dataframe

df = df.loc[df.index.repeat(df['a'])]   
df['c'] = df.groupby(level=0).cumcount() + 1
df = df.reset_index(drop=True)
print (df)
   a  b  c
0  1  x  1
1  2  y  1
2  2  y  2
3  3  z  1
4  3  z  2
5  3  z  3