On: "Visualizing Facebook Friends" was created using R

[arvinjoar]

'I created an ordering based on the length of the lines, so that longer lines were drawn “behind” the shorter, more local lines. Then I used colorRampPalette() to generate a color palette from black to blue to white, and colored the lines according to order they were drawn.'

If I am understanding this correctly (I'm probably not), longer lines would never be as bright as short lines. Why? Let's say hypothetically, that all Bostonians had at least 10 friends in Madrid, then wouldn't we want to see that as a white line on the chart? Please correct me if I am wrong.

[rlivsey → arvinjoar]

He addresses that in the paragraph before:

  My first attempt at plotting the data involved plotting 
  very transparent lines. Unfortunately there was just too
  much data to get a meaningful plot — even at very low 
  opacity, there were enough lines to make the entire 
  image just a bright blob.