How to convert string categorical variables into numerical variables in Python?
DATA MUNGING DATA CLEANING PYTHON MACHINE LEARNING RECIPES PANDAS CHEATSHEET     ALL TAGS

How to convert string categorical variables into numerical variables in Python?

How to convert string categorical variables into numerical variables in Python?

This recipe helps you convert string categorical variables into numerical variables in Python

0

Recipe Objective

Machine Learning Models can not work on categorical variables in the form of strings, so we need to change it into numerical form. This can be done by making new features according to the categories by assigning it values.

This python source code does the following:
1. Creates a data dictionary and converts it into pandas dataframe
2. Manually creates a encoding function
3. Applies the function on dataframe to encode the variable

So this is the recipe on how we can convert string categorical variables into numerical variables in Python.

Step 1 - Import the library

import pandas as pd

We have only imported pandas this is reqired for dataset.

Step 2 - Setting up the Data

We have created a dictionary and passed it through the pd.DataFrame to create a dataframe with columns 'name', 'episodes', 'gender'. data = {'name': ['Sheldon', 'Penny', 'Amy', 'Penny', 'Raj', 'Sheldon'], 'episodes': [42, 24, 31, 29, 37, 40], 'gender': ['male', 'female', 'female', 'female', 'male', 'male']} df = pd.DataFrame(data, columns = ['name','episodes', 'gender']) print(df)

Step 3 - Converting the values

We can clearly observe that in the column 'gender' there are two categories male and female, so for that we can assign number to each categories like 1 to male and 2 to female. def gender_to_numeric(x): if x=='female': return 2 if x=='male': return 1 df['gender_num'] = df['gender'].apply(gender_to_numeric) print(df) Here we are defining a function to assign numeric values and then we are applying of the feature 'gender'.
So the output comes as:

      name  episodes  gender
0  Sheldon        42    male
1    Penny        24  female
2      Amy        31  female
3    Penny        29  female
4      Raj        37    male
5  Sheldon        40    male

      name  episodes  gender  gender_num
0  Sheldon        42    male           1
1    Penny        24  female           2
2      Amy        31  female           2
3    Penny        29  female           2
4      Raj        37    male           1
5  Sheldon        40    male           1

Relevant Projects

Zillow’s Home Value Prediction (Zestimate)
Data Science Project in R -Build a machine learning algorithm to predict the future sale prices of homes.

Deep Learning with Keras in R to Predict Customer Churn
In this deep learning project, we will predict customer churn using Artificial Neural Networks and learn how to model an ANN in R with the keras deep learning package.

Data Science Project - Instacart Market Basket Analysis
Data Science Project - Build a recommendation engine which will predict the products to be purchased by an Instacart consumer again.

Identifying Product Bundles from Sales Data Using R Language
In this data science project in R, we are going to talk about subjective segmentation which is a clustering technique to find out product bundles in sales data.

German Credit Dataset Analysis to Classify Loan Applications
In this data science project, you will work with German credit dataset using classification techniques like Decision Tree, Neural Networks etc to classify loan applications using R.

Data Science Project in Python on BigMart Sales Prediction
The goal of this data science project is to build a predictive model and find out the sales of each product at a given Big Mart store.

Predict Employee Computer Access Needs in Python
Data Science Project in Python- Given his or her job role, predict employee access needs using amazon employee database.

Choosing the right Time Series Forecasting Methods
There are different time series forecasting methods to forecast stock price, demand etc. In this machine learning project, you will learn to determine which forecasting method to be used when and how to apply with time series forecasting example.

Machine Learning Project to Forecast Rossmann Store Sales
In this machine learning project you will work on creating a robust prediction model of Rossmann's daily sales using store, promotion, and competitor data.

Data Science Project-TalkingData AdTracking Fraud Detection
Machine Learning Project in R-Detect fraudulent click traffic for mobile app ads using R data science programming language.