These interactive grid-based visualizations were created with

Heat Map

This heat map illustrates connections between data in a matrix. Individual values are shown as colors – the Y-axis shows a list of titles of correspondence, the X-axis shows machine-extracted features, and the Z-axis shows dates. Hover the cursor over different points on the map to see specific connections.


Bar Chart

This bar chart shows relationships between two categories of data – machine-extracted features on the Y-axis and correspondence folders on the X-axis. The bars are shown in proportion to the features that they contain. Move the cursor over the bars to see the intersection between the data.



This timeline shows which machine-extracted features are occur in different correspondence over time. Move the toggle right or left to see the frequency of features by different years.

The sample data set used to create the Heat Map and Bar Chart visualizations can be downloaded here. The sample data set used to create the Timeline visualization can be downloaded here.