Searches for a nice-looking bin width to use to draw a dotplot such that the height of the dotplot fits within a given space (maxheight).

find_dotplot_binwidth(x, maxheight, heightratio = 1, stackratio = 1)

## Arguments

x

numeric vector of values

maxheight

maximum height of the dotplot

heightratio

ratio of bin width to dot height

stackratio

ratio of dot height to vertical distance between dot centers

## Value

A suitable bin width such that a dotplot created with this bin width and heightratio should have its tallest bin be less than or equal to maxheight.

## Details

This dynamic bin selection algorithm uses a binary search over the number of bins to find a bin width such that if the input data (x) is binned using a Wilkinson-style dotplot algorithm the height of the tallest bin will be less than maxheight.

This algorithm is used by geom_dotsinterval() (and its variants) to automatically select bin widths. Unless you are manually implementing you own dotplot grob or geom, you probably do not need to use this function directly

bin_dots() for an algorithm can bin dots using bin widths selected by this function; geom_dotsinterval() for geometries that use these algorithms to create dotplots.

## Examples


library(dplyr)
library(ggplot2)

x = qnorm(ppoints(20))
binwidth = find_dotplot_binwidth(x, maxheight = 4, heightratio = 1)
binwidth
#>  0.6533213

bin_df = bin_dots(x = x, y = 0, binwidth = binwidth, heightratio = 1)
bin_df
#> # A tibble: 20 × 3
#>         x     y   bin
#>     <dbl> <dbl> <dbl>
#>  1 -1.70  0.327     1
#>  2 -1.70  0.980     1
#>  3 -0.984 0.327     2
#>  4 -0.984 0.980     2
#>  5 -0.984 1.63      2
#>  6 -0.330 0.327     3
#>  7 -0.330 0.980     3
#>  8 -0.330 1.63      3
#>  9 -0.330 2.29      3
#> 10 -0.330 2.94      3
#> 11  0.330 0.327     4
#> 12  0.330 0.980     4
#> 13  0.330 1.63      4
#> 14  0.330 2.29      4
#> 15  0.330 2.94      4
#> 16  0.984 0.327     5
#> 17  0.984 0.980     5
#> 18  0.984 1.63      5
#> 19  1.70  0.327     6
#> 20  1.70  0.980     6

# we can manually plot the binning above, though this is only recommended
# if you are using find_dotplot_binwidth() and bin_dots() to build your own
# grob. For practical use it is much easier to use geom_dots(), which will
# automatically select good bin widths for you (and which uses
# find_dotplot_binwidth() and bin_dots() internally)
bin_df %>%
ggplot(aes(x = x, y = y)) +
geom_point(size = 4) +
coord_fixed() 