How to display only integer values on an axis usin

Question

I have the following plot:

library(reshape)
library(ggplot2)
library(gridExtra)
require(ggplot2)



data2<-structure(list(IR = structure(c(4L, 3L, 2L, 1L, 4L, 3L, 2L, 1L
), .Label = c("0.13-0.16", "0.17-0.23", "0.24-0.27", "0.28-1"
), class = "factor"), variable = structure(c(1L, 1L, 1L, 1L, 
2L, 2L, 2L, 2L), .Label = c("Real queens", "Simulated individuals"
), class = "factor"), value = c(15L, 11L, 29L, 42L, 0L, 5L, 21L, 
22L), Legend = structure(c(1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L), .Label = c("Real queens", 
"Simulated individuals"), class = "factor")), .Names = c("IR", 
"variable", "value", "Legend"), row.names = c(NA, -8L), class = "data.frame")
p <- ggplot(data2, aes(x =factor(IR), y = value, fill = Legend, width=.15))


data3<-structure(list(IR = structure(c(4L, 3L, 2L, 1L, 4L, 3L, 2L, 1L
), .Label = c("0.13-0.16", "0.17-0.23", "0.24-0.27", "0.28-1"
), class = "factor"), variable = structure(c(1L, 1L, 1L, 1L, 
2L, 2L, 2L, 2L), .Label = c("Real queens", "Simulated individuals"
), class = "factor"), value = c(2L, 2L, 6L, 10L, 0L, 1L, 4L, 
4L), Legend = structure(c(1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L), .Label = c("Real queens", 
"Simulated individuals"), class = "factor")), .Names = c("IR", 
"variable", "value", "Legend"), row.names = c(NA, -8L), class = "data.frame")
q<- ggplot(data3, aes(x =factor(IR), y = value, fill = Legend, width=.15))


##the plot##
q + geom_bar(position='dodge', colour='black') + ylab('Frequency') + xlab('IR')+scale_fill_grey() +theme(axis.text.x=element_text(colour="black"), axis.text.y=element_text(colour="Black"))+ opts(title='', panel.grid.major = theme_blank(),panel.grid.minor = theme_blank(),panel.border = theme_blank(),panel.background = theme_blank(), axis.ticks.x = theme_blank())

I want the y-axis to display only integers. Whether this is accomplished through rounding or through a more elegant method isn't really important to me.

Answer 1

These solutions did not work for me and did not explain the solutions.

The breaks argument to the scale_*_continuous functions can be used with a custom function that takes the limits as input and returns breaks as output. By default, the axis limits will be expanded by 5% on each side for continuous data (relative to the range of data). The axis limits will likely not be integer values due to this expansion.

The solution I was looking for was to simply round the lower limit up to the nearest integer, round the upper limit down to the nearest integer, and then have breaks at integer values between these endpoints. Therefore, I used the breaks function:

brk <- function(x) seq(ceiling(x[1]), floor(x[2]), by = 1)

The required code snippet is:

scale_y_continuous(breaks = function(x) seq(ceiling(x[1]), floor(x[2]), by = 1))

The reproducible example from original question is:

data3 <-
  structure(
    list(
      IR = structure(
        c(4L, 3L, 2L, 1L, 4L, 3L, 2L, 1L),
        .Label = c("0.13-0.16", "0.17-0.23", "0.24-0.27", "0.28-1"),
        class = "factor"
      ),
      variable = structure(
        c(1L, 1L, 1L, 1L,
          2L, 2L, 2L, 2L),
        .Label = c("Real queens", "Simulated individuals"),
        class = "factor"
      ),
      value = c(2L, 2L, 6L, 10L, 0L, 1L, 4L,
                4L),
      Legend = structure(
        c(1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L),
        .Label = c("Real queens",
                   "Simulated individuals"),
        class = "factor"
      )
    ),
    row.names = c(NA,-8L),
    class = "data.frame"
  )

ggplot(data3, aes(
  x = factor(IR),
  y = value,
  fill = Legend,
  width = .15
)) +
  geom_col(position = 'dodge', colour = 'black') + ylab('Frequency') + xlab('IR') +
  scale_fill_grey() +
  scale_y_continuous(
    breaks = function(x) seq(ceiling(x[1]), floor(x[2]), by = 1),
    expand = expand_scale(mult = c(0, 0.05))
    ) +
  theme(axis.text.x=element_text(colour="black", angle = 45, hjust = 1), 
        axis.text.y=element_text(colour="Black"),
        panel.grid.major = element_blank(),
        panel.grid.minor = element_blank(),
        panel.border = element_blank(),
        panel.background = element_blank(), 
        axis.ticks.x = element_blank())

Answer 2

With scale_y_continuous() and argument breaks= you can set the breaking points for y axis to integers you want to display.

ggplot(data2, aes(x =factor(IR), y = value, fill = Legend, width=.15)) +
    geom_bar(position='dodge', colour='black')+
    scale_y_continuous(breaks=c(1,3,7,10))

Answer 3

This is what I use:

ggplot(data3, aes(x = factor(IR), y = value, fill = Legend, width = .15)) +
  geom_col(position = 'dodge', colour = 'black') + 
  scale_y_continuous(breaks = function(x) unique(floor(pretty(seq(0, (max(x) + 1) * 1.1)))))

Answer 4

You can use a custom labeller. For example, this function guarantees to only produce integer breaks:

int_breaks <- function(x, n = 5) pretty(x, n)[pretty(x, n) %% 1 == 0] 

Use as

+ scale_y_continuous(breaks = int_breaks)

Answer 5

Google brought me to this question. I'm trying to use real numbers in a y scale. The y scale numbers are in Millions.

The scales package comma method introduces a comma to my large numbers. This post on R-Bloggers explains a simple approach using the comma method:

library(scales)

big_numbers <- data.frame(x = 1:5, y = c(1000000:1000004))

big_numbers_plot <- ggplot(big_numbers, aes(x = x, y = y))+
geom_point()

big_numbers_plot + scale_y_continuous(labels = comma)

Enjoy R :)

Answer 6

This answer builds on @Axeman's answer to address the comment by kory that if the data only goes from 0 to 1, no break is shown at 1. This seems to be because of inaccuracy in pretty with outputs which appear to be 1 not being identical to 1 (see example at the end).

Therefore if you use

int_breaks_rounded <- function(x, n = 5)  pretty(x, n)[round(pretty(x, n),1) %% 1 == 0]

with

+ scale_y_continuous(breaks = int_breaks_rounded)

both 0 and 1 are shown as breaks.

Example to illustrate difference from Axeman's

testdata <- data.frame(x = 1:5, y = c(0,1,0,1,1))

p1 <- ggplot(testdata, aes(x = x, y = y))+
  geom_point()


p1 + scale_y_continuous(breaks = int_breaks)
p1 + scale_y_continuous(breaks =  int_breaks_rounded)

Both will work with the data provided in the initial question.

Illustration of why rounding is required

pretty(c(0,1.05),5)
#> [1] 0.0 0.2 0.4 0.6 0.8 1.0 1.2
identical(pretty(c(0,1.05),5)[6],1)
#> [1] FALSE