I’m trying to align two color scales of ggplots with geom_contour_filled. Below is a minimum example.

library(ggplot2)

df_1 <- df_2 <- data.frame(
    n = rep(seq(0.1, 1, 0.1), each = 10),
    r = rep(seq(0.1, 1, 0.1), 10)
)

df_1$value <- df_1$n + df_1$r

df_2$value <- df_2$n + df_2$r + 0.2

p1 <- ggplot(df_1, aes(x = n, y = r, z = value)) +
    geom_contour_filled(breaks = seq(0, 2, length.out = 21)) +
    theme(legend.position = "bottom")

p2 <- ggplot(df_2, aes(x = n, y = r, z = value)) +
    geom_contour_filled(breaks = seq(0, 2, length.out = 21)) +
    theme(legend.position = "bottom")

p1+p2

The expectation both color scales should be the same. Aligning breaks doesn’t help, please do not combine two data frames, I need the freedom to use two ggplots separately.

Thanks.