- Data visualization in React using React D3
- How to get started with D3 and React
- Plotting a bar chart with D3 in React
- D3.js Axes
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Data visualization in React using React D3Data visualization is an important part of what we do at Aspen Mesh. When you implement a service mesh, it provides a huge trove of data about your services. Everything you need to know about how your services are communicating is available, but separating the signal from the noise is essential. Data visualization is a powerful tool to distill complex data sets into simple, actionable visuals. To build these visualizations, we use React and D3. React is great for managing a large application and organizing code into discrete components to keep you sane. D3 is magical for visuals on large data sets. Unfortunately, much of the usefulness of each library is lost and bugs are easy to come by when they are not conscientiously put together. In the following article, I will detail the pattern that I work with to build straight forward D3 based visualization components that fit easily within a large scale React application. The difficulty in putting both libraries together is each has its own way of manipulating the DOM. The simplest way to combine them is to let them do their own thing in isolation and act as black boxes to each other. I did not like this approach because it felt like jamming a separate D3 application inside of our existing React app. The code was structured differently, it had to be tested differently and it was difficult to use existing React components and event handlers. I kept researching and playing around with the code until I came on a pattern that addresses those issues. To illustrate the pattern, I will build out a bar graph that accepts an updating data set and transitions between them. The chart has an x axis based on date, and a y axis based on a numerical value. Each data points looks like this:. The root element to our chart is an SVG. The SVG is rendered through JSX, and subsequent chart elements, such as the axes and the bar elements, are passed in as child components. The SVG is responsible for setting the size and margin and dictating that to its child elements. It also creates scales based on the data and available size and passing the scales down. The SVG component can handle resizing as well as binding D3 panning and zooming functionality. The basic SVG component looks like this. There are two axis components for the left and bottom axes, and they receive the corresponding D3 scale object as a prop. The React ref object is key to linking up D3 and React. React will render the element, and so keep track of it in the Virtual DOM, and will then pass the ref to D3 so it can manage all the complex attribute math. On componentDidMount call, D3 selects the ref object and then calls the corresponding axis function on it, building the axis. On componentDidUpdatethe axis is redrawn with the updated scale after a D3 transition to give it a smooth animation. The bottom axis component looks as follows:. Data joins allow us to map DOM elements to specific data points and to recognize when those data points enter our set, exit, or are updated by a change in the data set. It is a powerful way to visually represent data constancy between changing data sets. It also allows us to update our chart and only redraw elements that change instead of redrawing the entire graph. Using D3 data joins, with the. The functions that would be run on.
How to get started with D3 and React
Plotting a bar chart with D3 in React
I'm a teacher-turned-software developer living in Helsinki, Finland. I love solving tricky problems and learning new things. My hobbies include reading and learning to drive a motorcycle. Data Driven Documents D3. It does this by binding data to the DOM Document Object Model and its elements and allowing them to transform when the data changes. We have some data which we update every time a librarian enters a new book. When the librarian adds a new book to the database, the data changes, and your graft shifts. When this data changes, our D3 graph updates the DOM to match the new data. D3 makes manipulating the website DOM easy. This means that you can use it to create, update and delete elements in the page structure. If you want to follow along with this example, you can use Create React App to create a simple React web app. If React is still unfamiliar to you, you can check out this tutorial from the React documentation. D3 makes manipulating the DOM easy. We can also use. The React library also manipulates the DOM. This means we have to make a little extra effort to get it to work together with D3. Luckily React already has a solution for allowing targeting and updating DOM elements. To do this, React uses references. Once you have selected the element you want to manipulate, you can start appending more elements to it. You can make D3 aware of your data by selecting DOM elements and attaching the data to them using. D3 has a method called. It signifies that these data elements need to be added to the DOM. Enters counterpart. We can use it to remove those elements together with remove, as in. What if we want to display the actual datapoint value? In D3, styles, attributes and other element properties can be set using functions. Functions in properties allow us to get creative with the elements. In this example from the D3 documentationa paragraph is given a random color using a function to set the elements style property. You can also use conditionals, just as in any function. However, adding inline styles is a tedious job, and we would like to use classes and ids instead so that we could set the styles in our CSS. To set attributes like classes and ids, we use. The code above could be refactored to. We can modify the animation to happen after 1 second using. We can also use functions together with transitions. For example, we can make our elements to appear in a staggered transition. The following example from the D3 documentation makes circles appear one at a time, using a delay function that takes dataPoint and iteration as parameters, and returns the iteration multiplied by Iteration refers to the position of the datapoint in the list of data.