How can I put log tickmarks on a secondary axis?

Question

I am doing a plot with a secondary y axis which is just a multiplicative scaling of the primary axis to display it in alternative units.

My primary y axis is log scaled, with log tickmarks from annotation_logticks. Is there any way to get log tickmarks in the secondary y axis in the scaled units? Currently they're in the primary units.

library(tidyverse)

x=c(100,1000000,100,1000000)
y=c(0.01,0.01,0.32,0.32)
z=c(1,1,0.5,0.5)
data <- data.frame(x,y,z)

data %>%
  ggplot(aes(x = x, y = y, z = z, fill = z)) +
  geom_raster(interpolate=TRUE) + 
  coord_fixed(ratio = 1, xlim = c(100,1000000), ylim=c(0.01,0.32)) +
  annotation_logticks(sides = "trbl") + 
  scale_x_log10() +
  scale_y_log10(sec.axis = sec_axis(~ . / 0.0714,
                                    breaks=c(0.2,0.5,1,2,5),
                                    name = "Sec. Axis")) + 
  scale_fill_continuous() +
  theme_bw()

^{Created on 2020-08-24 by the reprex package (v0.3.0)}

extra pics:

Currently, the right axis looks like:

I would like the axis to look like:

user_12500315 · Answer

There doesn't seem to be a way to do this directly with annotation_logticks, since the only positional parameter you can change is base. However, changing the base does not affect the position of the main breakpoint, which is determined by the primary axis values.

However, you can achieve a similar effect by manually setting the breaks and labels on the secondary axis:

data %>%
  ggplot(aes(x = x, y = y, z = z, fill = z)) +
  geom_raster(interpolate=TRUE) + 
  coord_fixed(ratio = 1, xlim = c(100,1000000), ylim=c(0.01,0.32)) +
  annotation_logticks(sides = "tbl") + 
  scale_x_log10() +
  scale_y_log10(sec.axis = sec_axis(~ . * 14,
                                    breaks= c(seq(0.1, 1, 0.1), 2:5),
                                    labels =  replace(character(14), 
                                                      c(2, 5, 10, 11, 14), 
                                                      c(0.2, 0.5, 1, 2, 5)),
                                    name = "Sec. Axis")) + 
  scale_fill_continuous() +
  theme_bw()

How can I put log tickmarks on a secondary axis?

1 Answers