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Preprocessing for Machine Learning in Python

IntermediateSkill Level

4.7+

Updated 12/2025

Learn how to clean and prepare your data for machine learning!

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PythonMachine Learning

4 hr

20 videos

62 Exercises

4,700 XP

66,197

Statement of Accomplishment

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Course Description

This course covers the basics of how and when to perform data preprocessing. This essential step in any machine learning project is when you get your data ready for modeling. Between importing and cleaning your data and fitting your machine learning model is when preprocessing comes into play. You'll learn how to standardize your data so that it's in the right form for your model, create new features to best leverage the information in your dataset, and select the best features to improve your model fit. Finally, you'll have some practice preprocessing by getting a dataset on UFO sightings ready for modeling.

Prerequisites

Cleaning Data in Python Supervised Learning with scikit-learn

1

Introduction to Data Preprocessing

In this chapter you'll learn exactly what it means to preprocess data. You'll take the first steps in any preprocessing journey, including exploring data types and dealing with missing data.

Introduction to preprocessing

Exploring missing data

Dropping missing data

Working with data types

Exploring data types

Converting a column type

Training and test sets

Class imbalance

Stratified sampling

2

Standardizing Data

This chapter is all about standardizing data. Often a model will make some assumptions about the distribution or scale of your features. Standardization is a way to make your data fit these assumptions and improve the algorithm's performance.

Standardization

When to standardize

Modeling without normalizing

Log normalization

Checking the variance

Log normalization in Python

Scaling data for feature comparison

Scaling data - investigating columns

Scaling data - standardizing columns

Standardized data and modeling

KNN on non-scaled data

KNN on scaled data

3

Feature Engineering

In this section you'll learn about feature engineering. You'll explore different ways to create new, more useful, features from the ones already in your dataset. You'll see how to encode, aggregate, and extract information from both numerical and textual features.

Feature engineering

Feature engineering knowledge test

Identifying areas for feature engineering

Encoding categorical variables

Encoding categorical variables - binary

Encoding categorical variables - one-hot

Engineering numerical features

Aggregating numerical features

Extracting datetime components

Engineering text features

Extracting string patterns

Vectorizing text

Text classification using tf/idf vectors

4

Selecting Features for Modeling

This chapter goes over a few different techniques for selecting the most important features from your dataset. You'll learn how to drop redundant features, work with text vectors, and reduce the number of features in your dataset using principal component analysis (PCA).

Feature selection

When to use feature selection

Identifying areas for feature selection

Removing redundant features

Selecting relevant features

Checking for correlated features

Selecting features using text vectors

Exploring text vectors, part 1

Exploring text vectors, part 2

Training Naive Bayes with feature selection

Dimensionality reduction

Training a model with PCA

5

Putting It All Together

Now that you've learned all about preprocessing you'll try these techniques out on a dataset that records information on UFO sightings.

UFOs and preprocessing

Checking column types

Dropping missing data

Categorical variables and standardization

Extracting numbers from strings

Identifying features for standardization

Engineering new features

Encoding categorical variables

Features from dates

Text vectorization

Feature selection and modeling

Selecting the ideal dataset

Modeling the UFO dataset, part 1

Modeling the UFO dataset, part 2

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FAQs

Is this course suitable for beginners in machine learning?

No. This is an advanced course with many prerequisites including pandas, scikit-learn, and statistics. You should have prior supervised learning experience.

What preprocessing techniques does this course cover?

You will learn data standardization, feature creation, feature selection, and how to handle missing data to prepare datasets for machine learning models.

What is the UFO sightings dataset used for?

The UFO sightings dataset is used in the final chapter as a hands-on exercise where you apply all the preprocessing techniques learned throughout the course.

How many chapters and exercises does this course have?

The course has 5 chapters and 70 exercises. Most learners complete it in about 3 hours.

Why is preprocessing important for machine learning?

Preprocessing ensures your data is in the right form for your model. Poorly prepared data can lead to inaccurate predictions regardless of which algorithm you choose.

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