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Building Data-Driven Applications with Danfo.js

You're reading from   Building Data-Driven Applications with Danfo.js A practical guide to data analysis and machine learning using JavaScript

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Product type Paperback
Published in Sep 2021
Publisher Packt
ISBN-13 9781801070850
Length 476 pages
Edition 1st Edition
Languages
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Authors (2):
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Stephen Oni Stephen Oni
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Stephen Oni
Rising Odegua Rising Odegua
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Rising Odegua
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Table of Contents (18) Chapters Close

Preface 1. Section 1: The Basics
2. Chapter 1: An Overview of Modern JavaScript FREE CHAPTER 3. Section 2: Data Analysis and Manipulation with Danfo.js and Dnotebook
4. Chapter 2: Dnotebook - An Interactive Computing Environment for JavaScript 5. Chapter 3: Getting Started with Danfo.js 6. Chapter 4: Data Analysis, Wrangling, and Transformation 7. Chapter 5: Data Visualization with Plotly.js 8. Chapter 6: Data Visualization with Danfo.js 9. Chapter 7: Data Aggregation and Group Operations 10. Section 3: Building Data-Driven Applications
11. Chapter 8: Creating a No-Code Data Analysis/Handling System 12. Chapter 9: Basics of Machine Learning 13. Chapter 10: Introduction to TensorFlow.js 14. Chapter 11: Building a Recommendation System with Danfo.js and TensorFlow.js 15. Chapter 12: Building a Twitter Analysis Dashboard 16. Chapter 13: Appendix: Essential JavaScript Concepts 17. Other Books You May Enjoy

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...
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