R and ggplot2: controlling scales in facet grid

I am plotting for a rowing boat the relation between cadence, speed, and going up- or down stream using facets in ggplot2:

library(tidyr)
library(ggplot2)

s <- function(d) ifelse(d < 500, "down", "up")

dist <- seq(1,1000)
cadence <- floor(25 + 7 * sin(dist/250))
speed <- 4+sin(dist/250)*2
stream <- s(dist)

df <- data.frame(dist,cadence,speed,stream)
g <- gather(df, variable, value, speed, cadence)

p <- ggplot(g, aes(dist, value)) +
    geom_line(aes(color=stream, group=1)) + 
    scale_x_continuous(name = "distance [m]") +
#    scale_y_continuous(sec.axis = sec_axis(~ (500/.),
#    name = "split 
展开收缩
",
#    breaks=c(90,95,100,105,110,115,120,125,130,140,150)),
#    limits=c(3.0,5.5),name="speed [m/s]") +
    facet_grid(variable ~ ., scales = "free_y")

I rely on scales="free_y" to get good automatic scaling of the Y axis. However, I would like to have more control and don't know how to achieve this:

• I would like to limit each y axis individually, if possible
• I would like to add a second y axis for the speed plot, showing a derived pace of time per 500m.

I know how to do this in individual plots but the facet grid makes sure the plots are properly aligned along the distance.

One option would be the ggh4x package which offers some options e.g. facetted_pos_scales to specify the scale individually for each facet and/or to add a secondary scale. Note however that we are still in the world of facets so you won't be able to set the the axis titles individually. To achieve that I would suggest to use patchwork.

library(ggh4x)
library(ggplot2)

ggplot(g, aes(dist, value)) +
  geom_line(aes(color = stream, group = 1)) +
  scale_x_continuous(name = "distance [m]") +
  facet_grid(variable ~ ., scales = "free_y") +
  facetted_pos_scales(
    y = list(
      variable == "speed" ~ scale_y_continuous(
        limits = c(3, 5.5), name = "speed [m/s]",
        sec.axis = sec_axis(~ (500 / .), name = "split 
展开收缩
", breaks = c(90, 95, 100, 105, 110, 115, 120, 125, 130, 140, 150))
      )
    )
  ) +
  theme(strip.placement = "outside")