Title: Map External Values To Dataframe Values in Pandas
Slug: pandas_map_values_to_values
Summary: Map External Values To Dataframe Values in Pandas
Date: 2016-05-01 12:00
Category: Python
Tags: Data Wrangling
Authors: Chris Albon

import modules



In [1]:

    
import pandas as pd

Create dataframe



In [2]:

    
raw_data = {'first_name': ['Jason', 'Molly', 'Tina', 'Jake', 'Amy'], 
        'last_name': ['Miller', 'Jacobson', 'Ali', 'Milner', 'Cooze'], 
        'age': [42, 52, 36, 24, 73], 
        'city': ['San Francisco', 'Baltimore', 'Miami', 'Douglas', 'Boston']}
df = pd.DataFrame(raw_data, columns = ['first_name', 'last_name', 'age', 'city'])
df









    Out[2]:






  
    
      
      first_name
      last_name
      age
      city
    
  
  
    
      0
      Jason
      Miller
      42
      San Francisco
    
    
      1
      Molly
      Jacobson
      52
      Baltimore
    
    
      2
      Tina
      Ali
      36
      Miami
    
    
      3
      Jake
      Milner
      24
      Douglas
    
    
      4
      Amy
      Cooze
      73
      Boston

Create a dictionary of values



In [3]:

    
city_to_state = { 'San Francisco' : 'California', 
                  'Baltimore' : 'Maryland', 
                  'Miami' : 'Florida', 
                  'Douglas' : 'Arizona', 
                  'Boston' : 'Massachusetts'}

Map the values of the city_to_state dictionary to the values in the city variable



In [4]:

    
df['state'] = df['city'].map(city_to_state)
df









    Out[4]:






  
    
      
      first_name
      last_name
      age
      city
      state
    
  
  
    
      0
      Jason
      Miller
      42
      San Francisco
      California
    
    
      1
      Molly
      Jacobson
      52
      Baltimore
      Maryland
    
    
      2
      Tina
      Ali
      36
      Miami
      Florida
    
    
      3
      Jake
      Milner
      24
      Douglas
      Arizona
    
    
      4
      Amy
      Cooze
      73
      Boston
      Massachusetts

	first_name	last_name	age	city
0	Jason	Miller	42	San Francisco
1	Molly	Jacobson	52	Baltimore
2	Tina	Ali	36	Miami
3	Jake	Milner	24	Douglas
4	Amy	Cooze	73	Boston