Problems with axis limits?

[gael-millot]

I believe I have some trouble when setting axis limits. The first is with scale_y_continuous():

# data
library(ggplot2)
ylim <- c(6, 30)
obs1 <- data.frame(
Time = 1:20, 
Group1 = rep(c("G", "H"), times = 10), 
Group2 = rep(c("A", "B"), each = 10)
)

obs1

# bars not displayed if 0 is not in the ylim range (test ylim = c(-1, 30))
# The problem is reported with a warning: all the values are removed when 0 is not in the range
p <- ggplot(data = obs1, mapping = aes(y = Time, x = Group2, fill = Group1)) 
p +
geom_bar(stat = "identity", position = position_dodge()) + 
scale_y_continuous(limits = sort(ylim))

# bars displayed whatever the ylim range
p + 
geom_bar(stat = "identity", position = position_dodge()) + 
coord_cartesian(ylim = sort(ylim))

The reason why I use coord_cartesian(ylim = sort(ylim)) in most of my functions. However, I encountered a new problem:

# y-axis disappearing
p + 
geom_point() + 
coord_cartesian(ylim = sort(ylim)) + 
scale_y_reverse()

# y-axis not disappearing
p + 
geom_point() + 
scale_y_continuous(limits = sort(ylim)) + 
scale_y_reverse()

Are all these expected ?

Many thanks for your help.

Best.

[yutannihilation]

Are all these expected ?

For the first one (bar chart), yes. For the second one, you need to reverse the range.

library(ggplot2)

ylim <- c(6, 30)
obs1 <- data.frame(
  Time = 1:20,
  Group1 = rep(c("G", "H"), times = 10),
  Group2 = rep(c("A", "B"), times = 10)
)

p <- ggplot(obs1, aes(Group2, Time, fill = Group2))

p +
  geom_point() +
  coord_cartesian(ylim = rev(ylim)) +
  scale_y_reverse()

^{Created on 2020-04-16 by the reprex package (v0.3.0)}

[gael-millot]

Many thanks for the feedback.

To make things clear:

1. the limits argument of scale_._continuous() and derivatives, like scale_._reverse(), lims(), etc., remove data outside the limits settings, which generates no bars using geom_bar() except if zero is in the axis range.

2. It is possible to prevent the data removal action of scale_._continuous() and derivatives, using a function from the scales package:

library(scales)
p <- ggplot(data = obs1, mapping = aes(y = Time, x = Group2, fill = Group1)) 
p +
geom_bar(stat = "identity", position = position_dodge()) + 
scale_y_continuous(limits = sort(ylim), oob = scales::rescale_none)

3. the coord_cartesian() function does not remove data, but performs a zoom. However, its xlim and ylim arguments must be in the same orientation than scale_._continuous() and derivatives. Otherwise no axis is drawn.

Is that correct ?

Thanks.

[yutannihilation]

Is that correct ?

Yes, I think your understanding is correct. That said,

Otherwise no axis is drawn.

I'm not sure if this is the desired behaviour (Should this be errored? Or, is this a bug?). Let me file a new issue for this.

[gael-millot]

Thanks a lot !

[urlrequestedgar40]

@gael-millot https://python-collections699.github.io/X8Qm7PR6N5LOLBbXUpU8WtQrRGoJi7Qia-DIlVBRoqztkPhw82yAHe1AJDmA_JNnBeI/