standardise: Standardise a summary to sum to one.
In hadley/bigvis: Tools for visualisation of big data sets

Standardise a summary to sum to one.

1	standardise(x, margin = integer())

`x`	a condensed summary. Must have `.count` variable.
`margin`	margins to standardise along. If `NULL`, the default, standardises the whole array.

b1 <- condense(bin(movies$year, 1))
d1 <- smooth(b1, 2, type = "reg")

if (require("ggplot2")) {

autoplot(b1)
autoplot(d1)

# Note change in x-axis limits
autoplot(standardise(d1))
}

# Can also standardise a dimension at a time
b2 <- with(movies, condense(bin(year, 2), bin(length, 10)))
b2 <- peel(b2, central = TRUE)

if (require("ggplot2")) {

autoplot(b2)
autoplot(standardise(b2))    # note legend
autoplot(standardise(b2, "year"))   # each row sums to 1
autoplot(standardise(b2, "length")) # each col sums to 1

base <- ggplot(b2, aes(length, .count)) +
  geom_line(aes(group = year, colour = year))
base
base %+% standardise(b2)  # Just affects y axis labels
base %+% standardise(b2, "year") # Makes year comparable
base %+% standardise(b2, "length") # Meaningless for this display

}