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You're reading from  Learning D3.js 5 Mapping - Second Edition

Product typeBook
Published inNov 2017
Reading LevelIntermediate
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ISBN-139781787280175
Edition2nd Edition
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Authors (3):
Thomas Newton
Thomas Newton
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Thomas Newton

Thomas Newton has over 20 years of experience in software engineering, creating highly scalable and flexible software solutions for clients. During this period, he has developed a broad range of expertise ranging from data visualizations, to large-scale cloud platforms, to continuous delivery and DevOps. When not going in a new technology, he spends time with his beautiful family.
Read more about Thomas Newton

Oscar Villarreal
Oscar Villarreal
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Oscar Villarreal

Oscar Villarreal has been building web applications and visualizations for the past 15 years. He's worked with all kinds of businesses and organizations globally, helping them visualize and interact with data in more meaningful ways. He enjoys spending time with his wife and kid, as well as hanging from the edge of a rock wall when climbing.
Read more about Oscar Villarreal

Lars Verspohl
Lars Verspohl
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Lars Verspohl

Lars Verspohl has been modeling and visualizing data for over 15 years. He works with businesses and organisations from all over the world to turn their often complex data into intelligible interactive visualizations. He also writes and builds stuff at datamake.io. His ideal weekend is spent either at a lake or on a mountain with his kids, although it can be hard to tear them away from the computer games he wrote for them.
Read more about Lars Verspohl

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The exit() function

We've discussed enter() and update. We've seen how one determines the starting point of our visualization and the other modifies its attributes based on new data coming in. However, the examples covered had the exact number of data elements with the same properties. What would happen if our new dataset had a different amount of items? What if it has fewer or more?

Let's take the update part of the previous example and modify it a bit to demonstrate what we're talking about (http://localhost:8080/chapter-3/example-5.html):

We can explain how this works with two small changes to the rectangles function:

var rectangles = function(svg) { 
var data = makeData((Math.random() * 5) + 1); 

Here, we tell the data function to create a random number of data objects:

  var rect = svg.selectAll('rect').data(data); 
 
  // Enter 
  rect.enter...
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Learning D3.js 5 Mapping - Second Edition
Published in: Nov 2017Publisher: ISBN-13: 9781787280175

Authors (3)

author image
Thomas Newton

Thomas Newton has over 20 years of experience in software engineering, creating highly scalable and flexible software solutions for clients. During this period, he has developed a broad range of expertise ranging from data visualizations, to large-scale cloud platforms, to continuous delivery and DevOps. When not going in a new technology, he spends time with his beautiful family.
Read more about Thomas Newton

author image
Oscar Villarreal

Oscar Villarreal has been building web applications and visualizations for the past 15 years. He's worked with all kinds of businesses and organizations globally, helping them visualize and interact with data in more meaningful ways. He enjoys spending time with his wife and kid, as well as hanging from the edge of a rock wall when climbing.
Read more about Oscar Villarreal

author image
Lars Verspohl

Lars Verspohl has been modeling and visualizing data for over 15 years. He works with businesses and organisations from all over the world to turn their often complex data into intelligible interactive visualizations. He also writes and builds stuff at datamake.io. His ideal weekend is spent either at a lake or on a mountain with his kids, although it can be hard to tear them away from the computer games he wrote for them.
Read more about Lars Verspohl