Dynamically select a good bin width for a dotplot
Source:R/binning_methods.R
find_dotplot_binwidth.RdSearches 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)
Arguments
| x | numeric vector of values |
|---|---|
| maxheight | maximum height of the dotplot |
| heightratio | ratio of bin width to dot height |
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
See also
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#> [1] 0.6533213#> # A tibble: 20 x 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()
