CODEWITHSUNDEEP
rggplot2axis-labels
MERose
MERose

Reputation: 4421

Distribute y axis ticks evenly between minum and maximum

I am about to plot some variables (in a boxplot, but that doesn't matter) where I want to display the minimum and the maximum on the ordinate scale (y-axis).

require(ggplot2)

y_min <- min(PlantGrowth$weight)
y_max <- max(PlantGrowth$weight)

ggplot(PlantGrowth, aes(x=group, y=weight)) +
  geom_boxplot() +
  ylim(y_min, y_max)

Result: No minimum and maximum display

I know, ylim() is not made to directly edit the y-axis labels, but when setting another range, it accidentally works:

ggplot(PlantGrowth, aes(x=group, y=weight)) +
  geom_boxplot() +
  ylim(0, 8)

The straightforward solution is probably defining the ticks yourself:

ggplot(PlantGrowth, aes(x=group, y=weight)) +
  geom_boxplot() +
  scale_y_continuous(breaks=c(seq(y_min, y_max, 1.25), y_max))

which almost always results in a varying distance of the last and the next-to-last tick of the y-axis. It'd requires to experiment with the by-argument of seq() until we a have an evenly ticked y-axis which includes the mininum and the maximum. Is there an elegant way? Not necessarily a ggplot2() solution, but one that works on seq()?

Upvotes: 0

Views: 1032

Answers (1)

Gregor Thomas
Gregor Thomas

Reputation: 145785

You seem to be looking for the length.out argument of seq rather than the by argument. That is, 

scale_y_continuous(breaks = seq(y_min, y_max, length.out = 6))

You may want to wrap the sequence in round() to avoid undue precision.

Upvotes: 4

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