The World Map of Metal?

A more literal map, illustrating the concentration of metal bands per capita. The source material is The Metal Archives, which is curated by a crack team of metalheads who ensure 'Bullet For My Valentine' never gets classified as heavy metal, ever. parse, dammit approved!

Unstartlingly, worldwide sales of white and black face paint look almost exactly the same. 

Hat tip: Neatorama

Standing on the Shoulders of Giants

Though technologically advanced, my Map of Rock is anemic in comparison to Pete Frame's Family of Rock.

I bow to You, O God,
Who appears in the astonishing form of Pete Frame

The curation task I took upon myself in mapping the various relationships between musicians is something that Pete has been doing for decades. 

For the obligatory bit of math here, the format used by Pete, though called a Family Tree, is not technically a tree. Trees, according to computer science, are graphs that have no direction, and are acyclic. Pete's trees are constrained by time and thus qualify as directed graphs. To illustrate, the Ozzy Ozbourne of 1985 can't loop back to join the Elf of 1967. Furthermore, this non-looping quality makes them a directed acyclic graph, a structure that has showed up regularly in my work. 

I'm both looking forward to, and dreading, trying to add all this data into my own map.

Hat tip to BoingBoing for pointing me to the Family of Rock. You've destroyed what little sleep I could have had over the next decade.