Chris Essig

Walkthroughs, tips and tricks from a data journalist in eastern Iowa

Archive for December 2012

Final infographics project

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For the last six weeks, I’ve taken a very awesome online course on data visualization called “Introduction to Infographics and Data Visualization” It is sponsored by the Knight Center for Journalism in Americas and taught by the extremely-talented Albert Cairo. If you have a quick second, check out his website because it’s phenomenal.

Anyways, we have reached the final week of the course and Cairo had us all make a final interactive project. He gave us free reign to do whatever we want. We just had to pick a topic we’re passionate about. Given that I was a cops and courts reporter for a year in Galesburg, Illinois before moving to Waterloo, Iowa, I am passionate about crime reporting. So I decided for my final project I’d examine states with high violent crime rates and see what other characteristics they have. Do they have higher unemployment rates? Or lower education rates? What about wage rates?

Obviously, this is the type of project that could be expanded upon. I limited my final project to just four topics mostly because of time constraints. I work a full time job, you know! Anyways, here’s my final project. Let me know if you have any suggestions for improvement.

teaser

About:

Data: Information for the graphic was collected from four different sources, which are all listed when you click on the graphic. I took the spreadsheets from the listed websites and took out what I wanted, making CSVs for each of the four categories broken down in the interactive.

Map: The shapefile for the United States was taken from the U.S. Census Bureau’s website. Find it by going to this link, and selecting “States (and equivalent)” from the dropdown menu. I then simplified the shapefile by about 90 percent using this website. Simplifying basically makes the lines on the states’ polygons less precise but dramatically reduces the size of the file. This is important because people aren’t going to want to wait all day for your maps to load.

Merging data with map: I then opened that shapefile with an awesome, open-source mapping program called QGIS. I loaded up the four spreadsheets of data in QGIS as well using the green “Add vector layer” button (This is important! Don’t use the blue “Create a Layer from a Delimited Text File” button). The shapefile and all the spreadsheets will now show up on the right side of the screen in QGIS under “Layers.”

Each spreadsheet had a row for the state name, which matched the state names for each row in the shapefile.  It’s important these state names match exactly. For instance, for crime data from the FBI I had to lowercase the state names. So I turned “IOWA” into “Iowa” before loading it into QGIS because all the rows in the shapefile were lowercase (“Iowa” in the above example).

Then you can open the shapefile’s properties in QGIS and merge the data from the spreadsheets with the data in the shapefile using the “Joins” tab. Finally, right click on the shapefiles layer then “Save As” then export it as a GeoJSON file. We’ll use this with the wonderful mapping library Leaflet.

qgis_teaser

Leaflet: I used Leaflet to make the map. It’s awesome. Check it out. I won’t get into how I made the map interactive with Javascript because it’s copied very heavily off the this tutorial put out by Leaflet. Also check it out. The only thing I did differently was basically make separate functions (mentioned in the tutorial) for each of my four maps. There is probably (definitely) a better way to do this but I kind of ran out of time and went with what I had. If you’re looking for the full code, go here and click “View Page Source.”

Design: The buttons used are from Twitter’s Bootstrap. I used jQuery’s show/hide functions to show and hide all the element the page. This included DIVs for the legend, map and header.

GeoJSON: The last thing I did was modify my GeoJSON file. You’ll notice how the top 10 states for violent crime rates are highlighted in black on the maps to more easily compare their characteristics across the maps. Well, I went into the GeoJSON and put all those 10 states attributes at the bottom of the file. That way they are loaded last on the map and thus appear on top of the other states. If you don’t do this, the black outlines for the states don’t show up very well and look like crap. Here’s GeoJSON file for reference.

Hopefully that will help guide others. If you have any questions, feel free to drop me a line. Thanks!

 

Written by csessig

December 11, 2012 at 12:13 am