Heatmap Calendars
This is a series of visualisations of the individual scrobble activity of selected users. In total it encompasses 8.7 million scrobbles across ~180 graphs.

The visualisation is a structured heatmap that is designed to reveal periodicities: years, months, day of week, hour of day.

Check out the slideshow in fullscreen mode, and the annotated version.

The layout is comprised of two nested grids. Each year of data is arranged in a row and horizontally grouped into 12 blocks, one for each month. This is the outer grid. Months are organised by an inner grid, where data is arranged in seven columns for the days of week and 24 rows for the hours of day. Weekdays are aggregated so that e.g. all Mondays of a particular month end up in the same column.

Colour is a measure of relative intensity:
grey → green → yellow → red. A light grey strip highlights the most active hours of the day across the entire period.

At its most basic level this visualisation shows how frequently someone has been scrobbling over time, which in itself probably isn't that interesting. But the particular layout reveals some patterns in everyone's listening habits that aren't obvious from just looking at a timeline. Lunch breaks, dinner, the commute — as long as it happens regularly and interferes with one's music listening you should have no trouble finding it in the graph. In a few graphs you can even see seasonal effects!

Frequently people's graphs are detailed enough to provide a fairly good summary of big life changes. New jobs, busy weekends, holidays, the month when they bought an iPod, or picked up running again, or moved to a different timezone, ... I found that showing these graphs to the people portrayed often stimulated interesting conversation about their habits and their choices.

Concept and code by Martin Dittus in 2010 and 2011, images published on 2011-08-31 under a CC by-nc licence. The original sketch was written with Spde in Scala, and later ported to plain Java. All data was acquired with the lastexport script.
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