Title: Encoding Ordinal Categorical Features
Slug: encoding_ordinal_categorical_features
Summary: How to encode ordinal categorical features for machine learning in Python.
Date: 2016-09-06 12:00
Category: Machine Learning
Tags: Preprocessing Structured Data
Authors: Chris Albon

Preliminaries



In [1]:

    
# Load library
import pandas as pd

Create Feature Matrix



In [6]:

    
# Create features
df = pd.DataFrame({'Score': ['Low', 
                             'Low', 
                             'Medium', 
                             'Medium', 
                             'High']})

# View data frame
df

Create Scale Map



In [7]:

    
# Create mapper
scale_mapper = {'Low':1, 
                'Medium':2,
                'High':3}

Map Scale To Features



In [8]:

    
# Map feature values to scale
df['Scale'] = df['Score'].replace(scale_mapper)

# View data frame
df