Convert angles to ggplot2 vjust

Usage

angle2vjust(theta, multiplier = 1.5, as_degrees = FALSE)

Arguments

theta: angle in radians
multiplier: distance from point
as_degrees: use degrees instead of radians

Value

numeric

Examples

library(tibble)
library(ggplot2)
library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union
xy_ratio <- pi
tibble(theta = seq(0,2*pi, length.out = 9),
       y =  sin(theta),
       slope = cos(theta) * xy_ratio,
       text_angle = atan(slope) + pi / 2) %>%
   ggplot(aes(theta,y)) +
     stat_function(fun = sin) +
     geom_point() +
     geom_label(aes(label = LETTERS[1:9],
                    vjust = angle2vjust(text_angle, multiplier = 1.5),
                    hjust = angle2hjust(text_angle, multiplier = 1.5)),
                label.size = NA,
                label.padding = unit(1, "mm")) +
  scale_x_continuous(expression(theta),
                     breaks = seq(0,2*pi, length.out = 9),
                    labels = label_parsed(c("0", "frac(pi,4)", "frac(pi,2)",
                                             "frac(3 * pi,4)", "pi", "frac(5*pi,4)",
                                             "frac(3 * pi,2)", "frac(7*pi,4)", "2*pi"))) +
  scale_y_continuous(expression(sin(theta))) +
  coord_fixed(ratio = xy_ratio, clip = "off") +
  theme_minimal()