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Using dictionary to remap values in Pandas DataFrame columns

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  • Last Updated : 23 Jan, 2019

While working with data in Pandas, we perform a vast array of operations on the data to get the data in the desired form. One of these operations could be that we want to remap the values of a specific column in the DataFrame. Let’s discuss several ways in which we can do that.

Given a Dataframe containing data about an event, remap the values of a specific column to a new value.

Code #1: We can use DataFrame.replace() function to achieve this task. Let’s see how we can do that.




# importing pandas as pd
import pandas as pd
  
# Creating the DataFrame
df = pd.DataFrame({'Date':['10/2/2011', '11/2/2011', '12/2/2011', '13/2/2011'],
                    'Event':['Music', 'Poetry', 'Theatre', 'Comedy'],
                    'Cost':[10000, 5000, 15000, 2000]})
  
# Print the dataframe
print(df)

Output :

Now we will remap the values of the ‘Event’ column by their respective codes.




# Create a dictionary using which we
# will remap the values
dict = {'Music' : 'M', 'Poetry' : 'P', 'Theatre' : 'T', 'Comedy' : 'C'}
  
# Print the dictionary
print(dict)
  
# Remap the values of the dataframe
df.replace({"Event": dict})

Output :

 

Code #2: We can use map() function to achieve this task.




# importing pandas as pd
import pandas as pd
  
# Creating the DataFrame
df = pd.DataFrame({'Date':['10/2/2011', '11/2/2011', '12/2/2011', '13/2/2011'],
                    'Event':['Music', 'Poetry', 'Theatre', 'Comedy'],
                    'Cost':[10000, 5000, 15000, 2000]})
  
# Print the dataframe
print(df)

Output :

Now we will remap the values of the ‘Event’ column by their respective codes.




# Create a dictionary using which we
# will remap the values
dict = {'Music' : 'M', 'Poetry' : 'P', 'Theatre' : 'T', 'Comedy' : 'C'}
  
# Print the dictionary
print(dict)
  
# Remap the values of the dataframe
df['Event']= df['Event'].map(dict)
  
# Print the DataFrame after modification
print(df)

Output :


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