Today’s note is not specific for BQ GIS, but is handy when doing geospatial or other types of visualization and the dimension you are interested in has big outliers. Such extreme values might make charts ugly, or squeeze the choropleth map’s effective color range.

As an example, you might have most values in 0 to 100 range, and a few values reach 1000. Sometimes these outliers are interesting, but in my case they were noise, and I wanted to ignore them. I used to adjust the chart’s range manually or add another color interval, but decided to automate it. This is simple, let’s just compute quantiles, and then trim the most extreme values. …

About

Michael Entin

Hi, I'm TL of BigQuery GIS project. Posting small recipes and various notes for BQ GIS users.

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