Creating new columns with Mapping function (Pandas .map() function):

In [47]:
import numpy as np
import pandas as pd 
from pandas import Series, DataFrame
In [48]:
# Creating DataFrame1

nan=np.nan

df1 = DataFrame ({ 'Category': (['Books', 'Computers', 'Home']), 'sales_Number': np.array([1,3,5])})

df1
Out[48]:
Category sales_Number
0 Books 1
1 Computers 3
2 Home 5
In [45]:
map1= {'Books':'44', 'Computers':"55", 'Home':'66'}

map1
Out[45]:
{'Books': '44', 'Computers': '55', 'Home': '66'}
In [46]:
df1['customer_number']= df1['Category'].map(map1)

df1
Out[46]:
Category sales_Number customer_number
0 Books 1 44
1 Computers 3 55
2 Home 5 66