Data Visualization

What would you call this chart?

I’m working on a visualization of people logging into SpatialKey, and I’ve come up with the following table/chart.

(larger version)

Each row represents one customer, and each cell is one day. If the cell is blue that means the customer logged in that day. Otherwise the cell is gray (lighter gray for weekends to give some context to the timeline). So cells are either on or off, I’m not trying to show how much usage there was on a particular day, just that there was some usage.

The only other thing beyond the on/off blue/gray state is I’m trying to highlight customers who have stopped logging in. So if a customer has previously been logging in regularly and then they stop for a long time, I highlight the row in red to show how long it’s been since we last saw the customer.

What kind of chart is this? There’s got to be a name, but I don’t know even know what to google to figure it out. I’ve created these before in Excel using conditional formatting of cell background color. This one is being created with d3.js using SVG (more posts on d3 will likely be coming).

The first thing I was reminded of was DNA sequencing using gel electrophoresis.

It also reminded me of the great Lite Brite that I used to play with as a kid.

So I’m currently going back and forth between “DNA Sequence chart” and “Lite Brite chart”, but there’s got to be a better term…