Adding different y-axis to an R-plot in GGPLOT2

Question

My current script and output figure are attached. The problem with the current script is that I cannot manage to plot Cars_Avg_Sunday, Cars_Carfree_sunday, Active_AvgSunday, Active_CarfreeSunday on the Y-AXIS on the right going from 0 to 400 instead of the left-axis from 0 to 40. I tried many alternative approaches but am not coming close to a real solution. The problem with the current script is thus that those 4 lines are plotted on the left instead the right y-axis.

Thanks in advance for your help in solving this issue!

Asthma_For_Excel <- data.frame(
      time = c("07:00", "08:00", "09:00", "10:00", "11:00", "12:00", "13:00", "14:00", "15:00", "16:00", "17:00", "18:00", "19:00", "20:00"),
      NO2_Avg_Sunday = c(25, 24, 22, 22, 21, 20, 19, 18, 19, 20, 22, 26, 30, 34),
      NO2_Carfree_Sunday = c(28.14285714, 27.28571429, 24.64285714, 18.78571429, 13.14285714, 9.571428571, 6.357142857, 6.071428571, 3.928571429, 3.642857143, 3.571428571, 4, 6.071428571, 18.28571429),
      Cars_Avg_Sunday = c(54.7, 75.7, 103.6666667, 158.6666667, 157.6666667, 198.3333333, 205.6666667, 210.6666667, 255.3333333, 221.3333333, 244, 259.3333333, 252.6666667, NA),
      CarS_Carfree_Sunday = c(65, 100, 61, 49, 64, 86, 98, 92, 94, 95, 80, 68, 162, NA),
      Active_AvgSunday = c(26.66666667, 25.66666667, 39, 47, 87, 141, 139.6666667, 149.3333333, 158.3333333, 168.6666667, 155.3333333, 146, 107.3333333, NA),
      Active_CarfreeSunday = c(9, 46, 58, 124, 194, 296, 301, 303, 429, 406, 304, 245, 128, NA)
)
    
# Remove rows with missing values
Asthma_For_Excel <- na.omit(Asthma_For_Excel)

# Plotting the data
ggplot(Asthma_For_Excel, aes(x = time, group = 1)) +
  geom_line(aes(y = NO2_Avg_Sunday, colour = "NO2 Avg Sunday")) +
  geom_line(aes(y = NO2_Carfree_Sunday, colour = "NO2 Car-Free Sunday")) +
  geom_line(aes(y = Cars_Avg_Sunday, colour = "Cars Avg Sunday")) +
  geom_line(aes(y = CarS_Carfree_Sunday, colour = "Cars Car-Free Sunday")) +
  geom_line(aes(y = Active_AvgSunday, colour = "Active Avg Sunday")) +
  geom_line(aes(y = Active_CarfreeSunday, colour = "Active Car-Free Sunday")) +
  scale_y_continuous(
    limits = c(0, 40),
    expand = c(0, 0),
    name = "NO2 Concentrations", 
    sec.axis = sec_axis(~.*10, name = "Traffic Counts"    )
  ) +
  labs(
    x = "Time",
     colour = "Legend"
  )

Does this answer your question? [Why geom\_line data is not plotting according to the secondary axis created in R?](https://stackoverflow.com/questions/70862356/why-geom-line-data-is-not-plotting-according-to-the-secondary-axis-created-in-r) — Omniswitcher, Jul 03 '23 at 12:06

score 0 · Answer 1 · answered Jul 03 '23 at 12:09

You might find the following useful.

Asthma_For_Excel |>
  tidyr::pivot_longer(!all_of("time")) |>
  mutate(value = ifelse(grepl("^NO", name), 1, 0.1) * value) |>
  ggplot(aes(x = time, y = value, colour = name, group = name)) +
  geom_line() +
  scale_y_continuous(
    limits = c(0, 45), # increase limit to avoid cutting off the line
    expand = c(0, 0),
    name = "NO2 Concentrations", 
    sec.axis = sec_axis(~.*10, name = "Traffic Counts")
  ) +
  labs(
    x = "Time",
    colour = "Legend"
  )

(Side note: there are philosophical issues with dual-axes plots, but that's probably not what you came to SO for...)

Adding different y-axis to an R-plot in GGPLOT2

1 Answers1