Data Visualization / Choropleth Map - Tips to start

Hello everyone,

I am trying to get moving on doing the Choropleth Map project for the Data Visualization certificate class. I’m finding these D3 maps progressively more difficult and been looking at the code for the example to wrap my head around it. However, it is difficult for me to parse. Any tips for what kind of things I should look into and learn to figure out how to do this? I’ve done a web search of course, and could go further, but I figured these forums are here for a reason :slight_smile:

I guess i’m looking for some direction, like… learn about a, b and c to get started. Of course, I understand all the basics that got me this far about JSON data and mapping across 2 dimensional coordinates in D3 and working a bit with SVGs in D3.

Thanks, Vlad

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This is the best resource available for exactly what the OP requested.

After reading this i was able to finish the rest of my D3 projects with a lot less hair pulling

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Thanks for the responses. Also, to anyone else looking for help, I found these two articles helpful:

Introduction to Digital Cartography: GeoJSON and D3.js

Making maps with D3:

V

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May I ask, why is Albers the correct projection?

@hreg it’s Albers USA, not just Albers: Conic projections | D3 by Observable

Also it seems like topojson can now be used instead of topojson-client: https://github.com/topojson/topojson-client/blob/master/README.md#feature

Also-also (for my fellow campers out there) I’m having success with Promise.all() to cleanly fetch and use multiple datasets at once:

Promise.all([
  d3.json("https://FIRST-CALL.json"),
  d3.json("https://SECOND-CALL.json")
]).then(([firstCallResult, secondCallResult]) => {
  console.log(firstCallResult);
  console.log(secondCallResult);
  // do stuff
})

This thread is definitely necessary to complete the project IMO. All you beautiful people are lifesavers!

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