The Bubbles Animation in Hans Roslings Talk

Yihui Xie & Lijia Yu 2017-04-04

In Hans Rosling’s attractive talk Debunking third-world myths with the best stats you've ever seen, he used a lot of bubble plots to illustrate trends behind the data over time. This function gives an imitation of those moving bubbles, besides, as this function is based on symbols, we can also make use of other symbols such as squares, rectangles, thermometers, etc.

Suppose we have observations of \(n\) individuals over ani.options('nmax') years. In this animation, the data of each year will be shown in the bubbles (symbols) plot; as time goes on, certain trends will be revealed (like those in Rosling’s talk). Please note that the arrangement of the data for bubbles (symbols) should be a matrix like \(A_{ijk}\) in which \(i\) is the individual id (from 1 to n), \(j\) denotes the \(j\)-th variable (from 1 to p) and \(k\) indicates the time from 1 to ani.options('nmax').

And the length of x and y should be equal to the number of rows of this matrix.

ani.options(interval = 0.2, nmax = 50)

## use default arguments (random numbers); you may try to find the real data
par(mar = c(4, 4, 0.2, 0.2))

plot of chunk demo-a

## rectangles
Rosling.bubbles(type = "rectangles", data = matrix(abs(rnorm(50 * 10 * 2)), ncol = 2))

plot of chunk demo-b