# Categorical sampling animation
# (from Fig 11 of Wild et al's RSS article)

# Data based on Census at School Table Maker
# https://www.censusatschool.org.nz/2011/table-maker/?f1=travel&f2=

modes <- c("walk", "car", "bus", "bike", "other")
travel <- factor(rep(modes,
                     c(7349, 8992, 6486, 1156, 263+311+384)))

# Take many samples from the pop and tabulate them
n <- 100
sn <- 100
samples <- lapply(1:n, function(i) { table(sample(travel, sn)) })

# Plot the samples (first as a barplot, all as horizontal bars)
library(grid)
library(lattice)
boxWidth <- unit(2, "cm")
barchart(samples[[1]],
         col=rgb(0,0,1,.2),
         ylim=c(0, max(sapply(samples, max))),
         horizontal=FALSE,
         box.width=boxWidth)
# Add the horizontal bars
trellis.focus("panel", 1, 1)
count <- 1
samplefun <- function(samp) {
    grid.segments(unit(1:5, "native") - 0.5*boxWidth,
                  unit(samp, "native"), 
                  unit(1:5, "native") + 0.5*boxWidth,
                  unit(samp, "native"),
                  gp=gpar(lwd=2, col=rgb(0,0,1,.2)),
                  name=paste("sample.line", count, sep="."))
    count <<- count + 1
}    
lapply(samples, samplefun)
trellis.unfocus()
# Animate the bar height
library(gridSVG)
time <- 10
grid.animate("plot_01.barchart.rect.panel.1.1",
             height=do.call("rbind", samples),
#              height=animUnit(unit(unlist(samples), "native"),
#                              id=rep(1:5, n)),
             duration=time, interpolate="discrete")
# Animate the visibility of the horizontal bars
for (i in 1:n) {
    grid.garnish(paste("sample.line", i, sep="."),
                 visibility="hidden")
    grid.animate(paste("sample.line", i, sep="."),
                 visibility=c("hidden", "visible"),
                 group=TRUE,
                 begin=i/n*time,
                 duration=.01)
}
gridToSVG("wild.svg")