Varying separation between tiles using geom_tile and height?

Question

Using geom_tile, I want to put a horizontal line in between each of the rows of data. It seems if I use colour in the aesthetics, it will put lines both horizontally and vertically, which is not what I want. In the past, I have just made the height of the tiles smaller so there is some separation between them. However, it seems the amount of space varies from row to row? Why is this, is there a way to make the separation the same throughout?

library(ggplot2)
gn <- c(rep("gn1", 5),  rep("gn2", 5),  rep("gn3", 5),  rep("gn4", 5),  rep("gn5", 5), 
    rep("gn6", 5),  rep("gn7", 5),  rep("gn8", 5),  rep("gn9", 5),  rep("gn10", 5),
    rep("gn11", 5), rep("gn12", 5), rep("gn13", 5), rep("gn14", 5), rep("gn15", 5),
    rep("gn16", 5), rep("gn17", 5), rep("gn18", 5), rep("gn19", 5))

smpl <- rep(c("smpl1", "smpl2", "smpl3", "smpl4", "smpl5"), 19)

mut1 <- c(0, 2, 3, 3, 0)
mut2 <- c(0, 2, 2, 0, 3)
mut3 <- c(2, 0, 2, 0, 3)
mut4 <- c(0, 0, 2, 2, 3)
mut5 <- c(0, 2, 3, 3, 2)

mut <- c(mut1, mut2, mut3, mut4, mut5, mut2, mut3, mut1, mut4, mut2,
     mut5, mut1, mut4, mut5, mut5, mut1, mut3, mut1, mut4)

mut <- factor(mut, levels=c(0,2,3))

tst <- data.frame(gn=gn, smpl=smpl, mut=mut)

ggplot(tst, aes(x=smpl, y=gn, fill=mut, height=0.95)) + 
    geom_tile() +
    guides(fill=F) +
    ylab("Genes") +
    xlab("Sample") +
    scale_fill_manual(values=c("#FFFFFF", "#00BFC4", "#F8766D")) +
    theme(panel.grid.major.y=element_blank()) +
    theme(panel.grid.major.x=element_blank()) +
    theme(panel.grid.minor.y=element_blank()) +
    theme(panel.grid.minor.x=element_blank()) +
    theme(panel.background=element_rect(fill="#000000")) +
    theme(axis.ticks.x=element_blank(),
          axis.text.x=element_blank(),
          axis.title.x=element_blank())

Huh -- I just made the plot myself and it seems to depend on the resolution you view the figure at -- I did plot zoom and it looked much better. Great MWE! — atiretoo

Julius Vainora Julius Vainora · Accepted Answer · 2018-03-07T02:00:55

Let

n1 <- length(unique(tst$gn))
n2 <- length(unique(tst$smpl))

be the numbers of parts of y and x axis respectively. We can then exploit geom_line to achieve the result:

ggplot(tst) + 
  geom_tile(aes(x = smpl, y = gn, fill = mut)) + # aes for geom_tile
  guides(fill = FALSE) + ylab("Genes") + xlab("Sample") +
  scale_fill_manual(values = c("#FFFFFF", "#00BFC4", "#F8766D")) +
  theme(panel.grid.major.y = element_blank()) +
  theme(panel.grid.major.x = element_blank()) +
  theme(panel.grid.minor.y = element_blank()) +
  theme(panel.grid.minor.x = element_blank()) +
  theme(panel.background = element_rect(fill = "#000000")) +
  theme(axis.ticks.x = element_blank(),
        axis.text.x = element_blank(),
        axis.title.x = element_blank()) +
  geom_line(data = data.frame(x = c(0, n2) + 0.5, y = rep(2:n1, each = 2) - 0.5),
            aes(x = x, y = y, group = y)) # Horizonal lines

Varying separation between tiles using geom_tile and height?

1 Answers