Gain insights into D3.js fundamentals, explore DOM manipulation, data binding, and SVG. Learn about creating maps, graphs, and network visualizations to master data-driven documentation.

Introduction to Visualization Using D3.js.png

In this course, you will learn the fundamentals of D3.js (stands for Data-Driven Documents), which is a JavaScript library mainly used for visualization.

In the first half of the course, you will cover DOM (Document Object Model) manipulation, method chaining, data binding, and data loading.

In the second half, you’ll cover visualization concepts and dive deep into SVG which is used to draw different geometrical shapes. After that, you’ll work with various maps and graphs in order to display your data. Lastly, you’ll learn about network visualization with the help of nodes and links.

By the end of this course, you will have a new, powerful data visualization library at your disposal.

Introduction to Visualization Using D3.js

## Problem statement
Add a tooltip to the treemap already drawn in the *Drawing a Treemap* [lesson](https://www.educative.io/pageeditor/10370001/4609988201807872/6320326233817088). The tooltip should show the name of the continent of the country over which the mouse has hovered.

## Expected output


<!DOCTYPE html>
<meta charset="utf-8" />
<script src="https://d3js.org/d3.v4.min.js"></script>
<body></body>


codemirror

## Coding exercise
The problem is designed to check your understanding of the tooltip and treemap, so you are encouraged to solve it on your own. If you are completely stuck, then refer to the next lesson, which will explain the solution in detail.

var margin = {top: 20, right: 150, bottom: 60, left: 80},
     width =400 - margin.left - margin.right,
     height =400 - margin.top - margin.bottom
var data={
    name:"world",
    children:
    [   
        {   
            name:"Asia",
            children:
            [
                {   name:"China",
                    population:250 //in millions
                },
                {    name:"India",
                    population:150 //in million
                }
            ]
        },
        {
            name:"Europe",
            children:
            [
                {   name:"Uk",
                    population:68 //in millions
                },
                {   name:"France",
                    population:65 //in million
                }
            ]
        },
        {   name:"North america",
            children:
            [
                {   name:"USA",
                    population:120 //in millions
                },
                {   name:"Canada",
                    population:50 //in million
                }
            ]
        }
    ]
}
// Add your tooltip here




var scale=d3.scaleOrdinal([
          "#00A5E3",
          "#FF96C5",
          "#00CDAC",])
var svg = d3.select("body") //create Svg element
   .append("svg")
   .attr('width', width + margin.right + margin.left)
   .attr('height', height + margin.top + margin.bottom)
   .style("border", "solid 1px red");
var treemap=d3.treemap()
              .size([ 400,400])
              .paddingInner(2)
var c_data=d3.hierarchy(data)
c_data.sum(d => d.population)
let cell=svg.selectAll('tree')
             .data(treemap(c_data).leaves())
             .enter()
             .append('g')
             .attr("transform",d => 'translate('+[d.x0, d.y0]+')')
cell.append('rect')
    .attr("width",d=> d.x1 - d.x0)
    .attr("height",d=> d.y1 - d.y0)
    .attr("fill",d => scale(d.parent.data.name))
    //Add your event listener here


    
cell.append('text')
    .text(d => d.data.name)
    .attr("alignment-baseline", "hanging")
    






# Problem statement
Add a tooltip to the treemap already drawn in the *Drawing a Treemap* [lesson](https://www.educative.io/pageeditor/10370001/4609988201807872/6320326233817088). The tooltip should show the name of the continent of the country over which the mouse has hovered.

# Expected output


# Coding exercise
The problem is designed to check your understanding of the tooltip and treemap, so you are encouraged to solve it on your own. If you are completely stuck, then refer to the next lesson, which will explain the solution in detail.

Can you implement a tooltip in a treemap that will show the name of the continent when we hover over the country in the treemap?

Introduction

D3.js Fundamentals

Scales

Drawing Basic Shapes

Chart Fundamentals

Network Visualization, Hierarchical Data, and Interactivity

Conclusion

Challenge: Add Tooltip to a Treemap

Problem statement

Expected output

Coding exercise