dataframe select columns by index code example

Example 1: pandas select column by index

#    A  B  C
# 0  1  3  5
# 1  2  4  6

column_B = a_dataframe.iloc[:, 1]
print(column_B)

# OUTPUT
# 0    3
# 1    4

Example 2: 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 3: get column pandas

column = df["column_name"]

Example 4: pandas df by row index

indices = [133, 22, 19, 203, 14, 1]
df_by_indices = df.iloc[indices, :]

Example 5: 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