library(ggplot2)

#example stored in baseplot
ID <- 1:400
values1 <- rnorm(200, mean=50, sd=10) 
values2 <- c(rnorm(100, mean=20, sd=10), rnorm(100, mean=40, sd=10))
df <- data.frame(ID, values1, values2)
baseplot <- ggplot(df, aes(values1, values2)) +
  geom_point(size=2) 
baseplot


#set defined axis ticks with breaks=c()
baseplot +
  scale_y_continuous(breaks=c(12, 30, 55)) 

#set regular ticks with breaks=seq(a, b, c)
baseplot +
  scale_x_continuous(breaks=seq(10, 90, 10)) +
  scale_y_continuous(breaks=seq(10, 90, 10))

#set regular ticks with breaks=seq(a, b, c) and keep the limits to 90
baseplot +
  scale_x_continuous(breaks=seq(10, 90, 10)) +
  scale_y_continuous(limits=c(NA,90), breaks=seq(10, 90, 10))

#set regular ticks with breaks=seq(a, b, c)
baseplot +
  scale_x_continuous(breaks=c(seq(10, 50, 5), seq(50, 90, 10))) +
  scale_y_continuous(breaks=c(seq(20, 60, 2.5), seq(10, 90, 10)))


#set ticks on log scales
baseplot + 
  scale_y_continuous(trans = "log10") +
  annotation_logticks(sides="l")