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

Essential functions and methods in Danfo.js

In this section, we will look at some important functions and methods in relation to Series and DataFrames. The methods in each of the data structures are a lot and we can always visit the documentation for more methods. This section will only mention some of the most commonly used methods:

  • loc and iloc indexing
  • Sorting: the sort_values and sort_index methods
  • Filter
  • Arithmetic operations such as add, sub, div, mul, and cumsum

loc and iloc indexing

Accessing DataFrame rows and columns is made easier with the loc and iloc methods; both methods allow you to specify the rows and columns you would like to access. For those of you coming from Python' pandas library, the loc and iloc format as implemented in Danfo.js should be familiar.

The loc method is used to access a DataFrame with an index that is not numeric, as follows:

df_index = df4.loc({rows:['Bellion','Rihanna','Drake...