CODEWITHSUNDEEP
rggplot2
Markm0705
Markm0705

Reputation: 1440

R ggplot set origin when using a log scale

The last line in the following code sets the origin of the plot at zero for the y-scale and the y-scale's limits. How do I do this for the x-scale when using a log10 grid?

breaks <- 10^(-10:10)                                      # break for major axis
minor_breaks <- rep(1:9, 21)*(10^rep(-10:10, each = 9))    # breaks for minor axis

ggplot(data = cars, aes(x = dist, y = speed)) +                    
  geom_point() +                                                   
  scale_x_log10(breaks = breaks, minor_breaks = minor_breaks) +   # use log10 scale for x  
  theme(panel.grid.major = element_line(colour = "grey50")) +
  theme(panel.grid.minor = element_line(colour = "grey70")) +
  theme_light(base_size = 12) +
  scale_y_continuous(expand = c(0, 0), limits = c(0,30))        # sets origin and limits for y-scale

Upvotes: 1

Views: 647

Answers (1)

Jon Spring
Jon Spring

Reputation: 66835

I suggest using a modified transformation, pseudo_log_trans, which accommodates zero values (and even negatives) by smoothly transitioning between a linear scale in [-1, 1] and a signed log scale beyond that range. The approximate point of transition can be modified using the first parameter, sigma.

ggplot(data = cars, aes(x = dist, y = speed)) +                    
    geom_point() +         
    scale_x_continuous(trans = scales::pseudo_log_trans(1)) +
    theme(panel.grid.major = element_line(colour = "grey50")) +
    theme(panel.grid.minor = element_line(colour = "grey70")) +
    theme_light(base_size = 12) +
    coord_cartesian(expand = FALSE,   # EDIT #2
                    xlim = c(0, 130), ylim = c(0, 30))

enter image description here

Here's how it transitions between the linear and log scales:

plot(scales::pseudo_log_trans(), xlim = c(-5, 10))
lines(scales::log_trans(), xlim = c(-5, 10), col = "red")

enter image description here

Upvotes: 3

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