Book Image

Building Data-Driven Applications with Danfo.js

By : Rising Odegua, Stephen Oni
Book Image

Building Data-Driven Applications with Danfo.js

By: Rising Odegua, Stephen Oni

Overview of this book

Most data analysts use Python and pandas for data processing for the convenience and performance these libraries provide. However, JavaScript developers have always wanted to use machine learning in the browser as well. This book focuses on how Danfo.js brings data processing, analysis, and ML tools to JavaScript developers and how to make the most of this library to build data-driven applications. Starting with an overview of modern JavaScript, you’ll cover data analysis and transformation with Danfo.js and Dnotebook. The book then shows you how to load different datasets, combine and analyze them by performing operations such as handling missing values and string manipulations. You’ll also get to grips with data plotting, visualization, aggregation, and group operations by combining Danfo.js with Plotly. As you advance, you’ll create a no-code data analysis and handling system and create-react-app, react-table, react-chart, Draggable.js, and tailwindcss, and understand how to use TensorFlow.js and Danfo.js to build a recommendation system. Finally, you’ll build a Twitter analytics dashboard powered by Danfo.js, Next.js, node-nlp, and Twit.js. By the end of this app development book, you’ll be able to build and embed data analytics, visualization, and ML capabilities into any JavaScript app in server-side Node.js or the browser.
Table of Contents (18 chapters)
1
Section 1: The Basics
3
Section 2: Data Analysis and Manipulation with Danfo.js and Dnotebook
10
Section 3: Building Data-Driven Applications

Transforming data

Data transformation is the process of converting data from one format (master format) into another (target format) based on defined steps/processes. Data transformation can be simple or complex, depending on the structure, format, end goal, size, or complexity of the dataset, and as such, it is important to know the features that are available in Danfo.js for doing these transformations.

In this section, we'll introduce some features available in Danfo.js for doing data transformation. Under each sub-section, we'll introduce a couple of functions, including fillna, drop_duplicates, map, addColumns, apply, query, and sample, as well as functions for encoding data.

Replacing missing values

Many datasets come with missing values and in order to get the most out of these datasets, we must do some form of data filling/replacement. Danfo.js provides a fillna method that, when given a DataFrame or Series, can automatically fill any missing field with...