Annotate below a ggplot2 graph - r

I would like plot a line below a ggplot2 graph with text above it, something like this:
where the starting and ending point of the gene on the x axis can be specified.
My attempt so far:
require(ggplot2)
require(grid)
require(gridExtra)
data = data.frame(y = -log10(runif(100)), x = 1:100)
p = ggplot(data=data, aes(x, y)) + geom_point()
p = p + theme(plot.margin=unit(c(1, 1, 5, 1), "lines"))
t1 = textGrob("Gene1")
p1 = p + annotation_custom(grob=t1, xmin=0, ymin=0, xmax = 3, ymax=-.1)
print(p1)
which gives:
If I try to move the text down by adjusting ymax, then it disappears.

In my answer, I have changed a couple things:
1 - I changed the name of your data to "df", as "data" can cause confusion between objects and arguments.
2 - I removed the extra panel space around the main data plot, so that the annotation wasn't so far away.
require(ggplot2)
require(grid)
require(gridExtra)
# make the data
df <- data.frame(y = -log10(runif(100)), x = 1:100)
p <- ggplot(data=df, aes(x, y)) + geom_point()
# remove this line of code:
# p <- p + theme(plot.margin=unit(c(1, 1, 5, 1), "lines"))
# set up the plot theme for the annotation
blank_axes_and_thin_margin <- theme(axis.text = element_text(color="white"),
axis.title = element_text(color="white"),
axis.ticks = element_blank(),
panel.grid = element_blank(),
panel.border = element_blank(),
plot.margin=unit(c(0, 2, 0,2),"mm"))
# define the position of the arrow (you would change this part)
arrow_start <- min(df$x)
arrow_end <- mean(c(min(df$x), max(df$x)))
arrow_height <- 1
# here's the rectangle with the arrow
t2 <- ggplot(df, aes(x,y))+
theme_bw()+
geom_rect(aes(xmin=min(x), xmax = max(x)),
ymin=0, ymax=4,fill="gray50")+
coord_cartesian(ylim=c(0,4))+
annotate(geom="text", label="Gene1",
x=20, y=2, size=6, color="black")+
geom_segment(x=arrow_start, xend=arrow_end,
y=arrow_height, yend=arrow_height,
color="black", arrow=arrow(ends="both"))+
blank_axes_and_thin_margin
t2
# arrange the graphic objects here
# I use arrangeGrob because it allows you to use ggsave(), unlike grid.arrange
plot_both <- arrangeGrob(p, t2, nrow=2, heights=unit(c(0.75,0.25), "null"))
plot_both
# ta-da !

you can turn clipping off,
g <- ggplotGrob(p1)
g$layout$clip[g$layout$name == "panel"] <- "off"
grid.newpage()
grid.draw(g)

Related

How to sensibly align two legends when using cowplot in R?

A similar question was asked here, however I cant adapt the answer to my issue.
I am trying to correctly align two legends when using cowplot. For example, if I create some data and a cowplot with two legends like so:
library(cowplot)
library(ggplot2)
# create some data
dat <- NULL
for(i in 1:20){
x <- LETTERS[1:5]
y <- paste0("var", seq(1,5))
dat[[i]] <- expand.grid(X=x, Y=y)
dat[[i]]$Z <- runif(25, 0, 1)
}
# plotting function
plotFun <- function(data){
ggplot(data, aes(X, Y, fill= Z)) +
geom_tile() +
theme(aspect.ratio = 1,
legend.justification = c(0,1),
axis.text.x=element_blank(),
axis.ticks.x=element_blank(),
axis.text.y=element_blank(),
axis.ticks.y=element_blank()) +
xlab("") + ylab("")
}
# set up to plot on a grid
allPlots <- lapply(dat, plotFun)
allPlotsAlter <- lapply(allPlots, function(x) x + theme(legend.position = "none"))
n <- length(allPlotsAlter)
nRow <- floor(sqrt(n))
plotGrid <- gridExtra::arrangeGrob(grobs=allPlotsAlter, nrow=nRow)
# create a different type of legend
newPlot <- ggplot(iris, aes(x = Sepal.Length, y = Petal.Length, fill = Species)) +
geom_bar(stat = 'identity') + theme(legend.justification = c(0,1))
# get both legends and combine
legend <- cowplot::get_legend(allPlots[[1]])
legend1 <- cowplot::get_legend(newPlot)
combineLegend <- cowplot::plot_grid(
legend,
legend1,
nrow = 2)
# now make plot
cowplot::plot_grid(plotGrid,
combineLegend,
rel_widths = c(0.9, 0.11),
ncol = 2)
That creates this type of plot:
As you can see, the two legends have quite a bit of vertical space between them and they are not centred with the plot.
Is there a way to align the two legends so they look something like this:
I'm not sure if it is possible using cowplot... or is there a way to maybe use ggplot's annotate to place the legends?
I would probably go for patchwork, as Stefan suggests, but within cowplot you probably need to adjust the legend margins:
theme_margin <- theme(legend.box.margin = margin(100, 10, 100, 10))
legend <- cowplot::get_legend(allPlots[[1]] + theme_margin)
legend1 <- cowplot::get_legend(newPlot + theme_margin)
combineLegend <- cowplot::plot_grid(
legend,
legend1,
nrow = 2)
# now make plot
cowplot::plot_grid(plotGrid,
combineLegend,
rel_widths = c(0.9, 0.11),
ncol = 2)
If switching to another package is an option for you I would suggest to use patchwork to glue your plots together. One feature offered by patchwork is that using plot_spacer you could easily add some empty panels above and below your legends to "move" them to the center and thereby getting rid of the empty space. Depending on your final result or the height of your final plot you probably have to play a bit around with the heights and/or widths arguments:
library(cowplot)
library(ggplot2)
library(patchwork)
set.seed(123)
# create some data
dat <- NULL
for (i in 1:20) {
x <- LETTERS[1:5]
y <- paste0("var", seq(1, 5))
dat[[i]] <- expand.grid(X = x, Y = y)
dat[[i]]$Z <- runif(25, 0, 1)
}
# plotting function
plotFun <- function(data) {
ggplot(data, aes(X, Y, fill = Z)) +
geom_tile() +
theme(
aspect.ratio = 1,
legend.justification = c(0, 1),
axis.text.x = element_blank(),
axis.ticks.x = element_blank(),
axis.text.y = element_blank(),
axis.ticks.y = element_blank()
) +
labs(x = NULL, y = NULL)
}
# set up to plot on a grid
allPlots <- lapply(dat, plotFun)
allPlotsAlter <- lapply(allPlots, function(x) x + theme(legend.position = "none"))
n <- length(allPlotsAlter)
nRow <- floor(sqrt(n))
plotGrid <- wrap_plots(grobs = allPlotsAlter, nrow = nRow)
# create a different type of legend
newPlot <- ggplot(iris, aes(x = Sepal.Length, y = Petal.Length, fill = Species)) +
geom_bar(stat = "identity") +
theme(legend.justification = c(0, 1))
# get both legends and combine
legend <- cowplot::get_legend(allPlots[[1]])
legend1 <- cowplot::get_legend(newPlot)
combineLegend <- plot_spacer() + legend + legend1 + plot_spacer() + plot_layout(ncol = 1, heights = c(.5, 1, 1, .5))
wrap_elements(plotGrid) + combineLegend + plot_layout(widths = c(4, 1))

Decrease margins between plots when using cowplot

I would like to combine some graphs together using cowplot. But I cannot change the margin sizes. I want to use only one y-axes, but than the margin is still quite large, which I want to decrease. I have used the plot.margin code from ggplot, although that works when I look at the single plot, it doesn't seem to work when the plots are combined.
I have made some example code:
library(ggplot2)
library(cowplot)
x <- c("a", "b")
y1 <- c(3,6)
y2 <- c(10,15)
data1 <- data.frame(x,y1)
data2 <- data.frame(x, y2)
ylab1 <- ylab("Very nice y values")
xlab1 <- xlab("Very nice factors")
plot1 <- ggplot(data1, aes(x=x, y = y1)) +
geom_bar(stat ="identity", position=position_dodge(), fill = "grey")+
theme(plot.margin = unit(c(0.5,0.5,0.5,0.5), "cm")) + xlab1 + ylab1
plot1
ylab2 <- ylab("")
xlab2 <- xlab("Very nice factors")
plot2 <- ggplot(data2, aes(x=x, y = y2)) +
geom_bar(stat = "identity",position=position_dodge(), fill = "grey")+
theme(plot.margin = unit(c(0.5,0.5,0.5,-0.5), "cm")) + xlab2 + ylab2
plot2
plot3 <- plot_grid(plot1, plot2, labels = c("A", "B"), align = "hv",nrow = 1, ncol = 2)
plot3 # Quite large margin between the two plots
I am aware that I could avoid this problem by using facets, however my real plot is rather more complicated than this graph.
Increasing the space between plots in plot_grid was also addressed in this issue.
An extra interesting solution is the one suggested in this comment - try to add an extra empty plot between the two plots and adjust the relative columns widths:
plot4 <- plot_grid(plot1, NULL, plot2, rel_widths = c(1, 0, 1), align = "hv",
labels = c("A", "B"), nrow = 1)
plot4
Can even try negative values in rel_widths, which gives better results:
plot5 <- plot_grid(plot1, NULL, plot2, rel_widths = c(1, -0.1, 1), align = "hv",
labels = c("A", "B"), nrow = 1)
plot5
So, try a combination of adjusting the plot.margin (as answered by #J.Con) and adding an extra empty plot with tweaking rel_widths.
EDIT 2019-12-11
Also check out this comment of the author of cowplot (Claus Wilke):
For those kinds of problems I would now recommend the patchwork library. It's inherently difficult with plot_grid(), due to its underlying design
So, a fast example with patchwork based on their vignette Adding Annotation and Style goes like this:
library(patchwork)
plot3 <- plot1 + plot2 +
plot_annotation(tag_levels = 'A') &
theme(plot.tag = element_text(size = 8))
plot3
Created on 2019-12-11 by the reprex package (v0.3.0)
Your plot.margins were actually working against you. Set them to zero to fill up that white space.
plot1 <- ggplot(data1, aes(x=x, y = y1)) +
geom_bar(stat ="identity", position=position_dodge(), fill = "grey")+
theme(plot.margin = unit(c(0,0,0,0), "cm")) + xlab1 + ylab1
plot1
ylab2 <- ylab("")
xlab2 <- xlab("Very nice factors")
plot2 <- ggplot(data2, aes(x=x, y = y2)) +
geom_bar(stat = "identity",position=position_dodge(), fill = "grey")+
theme(plot.margin = unit(c(0,0,0,0), "cm")) + xlab2 + ylab2
plot2
plot3 <- plot_grid(plot1, plot2, labels = c("A", "B"), align = "hv",nrow = 1, ncol = 2)
plot3

Specify plot height in plot_grid with 'hv' aligment: cowplot

I have been using the plot_grid command from cowplot to arrange my plots. I use the labeling feature, and my plots all look the same in that regard. However, when I 'hv' align some plots that have very different y-axis limits, such as the one below, it appears the height of the plot with shortest range of y is used.
If I just 'v' align the plot it looks better in some respects, but it is hard to resize the plot and have the labels looking good. I'd prefer the plot height not consider the x-axis labels, etc, like above.
Using gtables, I can get the desired width/height (below), but these leaves me without the consistent labels across all the figures in a document. Can I use the 'hv' alignment with cowplot and specify which plot height to use?
library(ggplot2)
library(dplyr)
library(scales)
library(grid)
library(cowplot)
data(iris)
iris <- iris %>% mutate(Petal.Width2 = ifelse(Species == "setosa", Petal.Width * 75, Petal.Width))
p1 <- ggplot(data=iris, aes(x = factor(Species), y=Sepal.Width)) +
geom_bar(stat="identity") +
labs(x = NULL, y = "Plot One") +
scale_y_continuous(labels = percent) +
theme(axis.text.x = element_blank(),
axis.title.y = element_text(vjust=1), plot.margin=unit(c(2,2,0,2),"mm"))
p2 <- ggplot(data=iris, aes(x = factor(Species), y=Petal.Width2)) + geom_bar(stat="identity") +
labs(x = NULL, y = "Plot Two") +
scale_y_continuous(labels = percent) +
theme(axis.text.x = element_blank(),
axis.title.y = element_text(vjust=1), plot.margin=unit(c(0,2,0,2),"mm"))
p3 <- ggplot(data=iris, aes(x = factor(Species), y=Petal.Length*0+.01)) + geom_bar(stat="identity") +
labs(x = "SPECIES", y = "The Third plot") +
scale_y_continuous(labels = percent) +
theme( axis.title.y = element_text(vjust=1, color="blue"), plot.margin=unit(c(0,2,0,2),"mm"),
axis.text.x = element_text(angle = 90, hjust=1, vjust=1,face ="italic", size=10))
plot_grid(p1,p2,p3,ncol=1, align="v", labels=c("A", "B", "C"))
# https://stackoverflow.com/a/27408589/1670053
plots <- list(p1, p2, p3)
grobs = lapply(plots, ggplotGrob)
g = do.call(rbind, c(grobs, size="first"))
g$widths = do.call(unit.pmax, lapply(grobs, "[[", "widths"))
grid.newpage()
grid.draw(g)
it's easy as to add labels,
plots <- list(p1, p2, p3)
grobs = lapply(plots, ggplotGrob)
library(gridExtra)
g = do.call(rbind, grobs) # uses gridExtra::rbind.gtable
panels <- g$layout[g$layout$name=="panel",]
g <- gtable::gtable_add_grob(g, lapply(LETTERS[1:nrow(panels)],
textGrob, vjust=1, y=1,
gp=gpar(fontface=2)),
t=panels$t, l=2)
grid.newpage()
grid.draw(g)

Arrange ggplot plots (grobs with same widths) using gtable to create 2x2 layout

I am attempting to use grobs and gtable to arrange 4 (ggplot2) plots into a 2x2 grid. I don't know how to set widths, and also a non- 1xn, or nx1 arrangement.
Using this code:
data(iris)
a <- ggplot(iris, aes(x=Species, y=Petal.Width)) + geom_boxplot(color="black") + ylab(expression(Foo~Bar~(g~cm^{-3})))
b <- ggplot(iris, aes(x=Species, y=Petal.Length*100)) + geom_boxplot(color="black") + ylab("foobar (mm)")
c <- ggplot(iris, aes(x=Species, y=Sepal.Width)) + geom_boxplot(color="black") + ylab("foobar (%)")
d <- ggplot(iris, aes(x=Species, y=log10(Sepal.Length))) + geom_boxplot(color="black") + ylab("foobar (cm)")
plots <- list(a,b,c,d)
grobs = lapply(plots, ggplotGrob)
g = do.call(rbind, c(grobs, size="first"))
g$widths = do.call(unit.pmax, lapply(grobs, "[[", "widths"))
grid.newpage()
grid.draw(g)
I can create the following 1x4 arrangement.
If I use grid.arrange for two columns, on the 4 plots, the plots are of different widths.
How can I bind plots into a gtable for a 4 x 4 arrangement?
# I thought maybe I could cbind, then rbind, but this does not work
plots1 <- list(a,b)
plots2 <- list(c,d)
grobs1 = lapply(plots1, ggplotGrob)
grobs2 = lapply(plots2, ggplotGrob)
g1 = do.call(cbind, c(grobs1, size="first"))
g2 = do.call(cbind, c(grobs2, size="first"))
# g3 = do.call(rbind, c(g1,g2, size="first")) #this does not work
I think you already had the answer.
Your last line returns an error, but a small edit results in a combined plot where widths within columns are the same:
g3 = do.call(rbind, c(list(g1,g2), size="first")) #combine g1 and g2 into a list
A sidenote for aesthetics/reference:
If your x-axis is the same, you can drop it from the top two plots.
library(ggplot2); library(gridExtra); library(grid)
# Tweak the margins to use up empty space. Margins: Top, Right, Bottom, Left
# For reference: a1= top left, b1= top right
# c1= bottom left, d1= bottom right
a1 <- a + theme(axis.title.x = element_blank(),
axis.text.x = element_blank(),
axis.ticks.x= element_blank(),
plot.margin= unit(c(1, 1, -0.5, 0.5), "lines") )
b1 <- b + theme(axis.title.x = element_blank(),
axis.text.x = element_blank(),
axis.ticks.x= element_blank(),
plot.margin= unit(c(1, 1, -0.5, 0.5), "lines") )
c1 <- c + theme(plot.margin= unit(c(0, 1, 0.5, 0.5), "lines") )
d1 <- d + theme(plot.margin= unit(c(0, 1, 0.5, 0.5), "lines") )
grobz <- lapply(list(a1, b1, c1, d1), ggplotGrob)
grobz.plot <- arrangeGrob( grobs = list(rbind(grobz[[1]], grobz[[3]], size = "last"),
rbind(grobz[[2]], grobz[[4]], size = "last")),
ncol = 2)
grid.draw(grobz.plot)
These StackOverflow questions are helpful in aligning plots:
Using rbind in gtable to set plot width (Baptiste) [link]
Relative panel heights in gtable (Baptiste) [link]
Plot widths and legends [link]
Pretty similar to the above, but using gtable functions*
library(ggplot2)
pl <- list(ggplot() + xlab("x"),
ggplot() + ylab("y"),
ggplot() + ylab("y"),
ggplot() + ggtitle("title") + xlab("x"))
library(grid)
library(gridExtra)
gl <- lapply(pl, ggplotGrob)
# gt <- cbind(rbind(gl[[1]], gl[[3]]),
# rbind(gl[[2]], gl[[4]]))
# alternative to remove x-axes of top row of plots
gt <- cbind(rbind(gl[[1]][1:3,], gl[[3]]),
rbind(gl[[2]][1:3,], gl[[4]]))
grid.newpage()
grid.draw(gt)
*: actually, since gtable doesn't allow the use of pmax when comparing units, this is using a drop-in replacement from the dev version of gridExtra.
would this work for you
library(cowplot)
library(ggplot2)
data(iris)
a <- ggplot(iris, aes(x=Species, y=Petal.Width)) + geom_boxplot(color="black") + ylab(expression(Foo~Bar~(g~cm^{-3}))) + theme_grey()
b <- ggplot(iris, aes(x=Species, y=Petal.Length*100)) + geom_boxplot(color="black") + ylab("foobar (mm)") + theme_grey()
c <- ggplot(iris, aes(x=Species, y=Sepal.Width)) + geom_boxplot(color="black") + ylab("foobar (%)") + theme_grey()
d <- ggplot(iris, aes(x=Species, y=log10(Sepal.Length))) + geom_boxplot(color="black") + ylab("foobar (cm)") + theme_grey()
plot_grid(a,b, c, d, ncol=2,align="v")

Label individual panels in a multi-panel ggplot2

I'm interested in trying to create simple corner labels for a multipanel figure I am preparing in ggplot. This is similar to this previously asked question, but the answers only explained how to include a label at the top of the plot, not produce a corner label in the format required by many journals. I hope to replicate something similar to the plotrix function corner.label() in ggplot2.
Here is an example using plottrix of what I would like to recreate in ggplot2.
require(plotrix)
foo1<-rnorm(50,25,5)
foo2<-rpois(50,25)
foo3<-rbinom(50,25,0.5)
foo4<-rnbinom(50,25,0.5)
par(mfrow=c(2,2))
hist(foo1)
corner.label(label='a',figcorner=T)
hist(foo2)
corner.label(label='b',figcorner=T)
hist(foo3)
corner.label(label='c',figcorner=T)
hist(foo4)
corner.label(label='d',figcorner=T)
This produces the following:
Thanks for any help in advance!
Two recent changes have made this a lot easier:
The latest release of ggplot2 has added the tag caption which can be used to label subplots.
The package patchwork makes it really easy to plot multiple ggplot objects. https://github.com/thomasp85/patchwork
This means that no altering of grobs is required. Adapting the reproducible example provided by Kev:
library(ggplot2)
# install.package("patchwork")
library(patchwork)
a <- 1:20
b <- sample(a, 20)
c <- sample(b, 20)
d <- sample(c, 20)
mydata <- data.frame(a, b, c, d)
myplot1 <- ggplot(mydata, aes(x=a, y=b)) + geom_point() + labs(tag = "A")
myplot2 <- ggplot(mydata, aes(x=b, y=c)) + geom_point() + labs(tag = "B")
myplot3 <- ggplot(mydata, aes(x=c, y=d)) + geom_point() + labs(tag = "C")
myplot4 <- ggplot(mydata, aes(x=d, y=a)) + geom_point() + labs(tag = "D")
myplot1 + myplot2 + myplot3 + myplot4
Extension: Changing Style:
If you want to change the labelling style, you can either set this individually for each plot or set a theme default. I would recommend the second approach. Add the following line before you build your plots to make the font bold and blue
ggplot2::theme_update(plot.tag = element_text(face = "bold", colour = "blue"))
For more information on customising the theme of ggplot2, see here.
I had the same problem and came up with the following solution, which is a bit different:
loading r packages
library(ggplot2)
library(grid)
library(gridExtra)
example data
a <- 1:20
b <- sample(a, 20)
c <- sample(b, 20)
d <- sample(c, 20)
create a data frame
mydata <- data.frame(a, b, c, d)
create example plots
myplot1 <- ggplot(mydata, aes(x=a, y=b)) + geom_point()
myplot2 <- ggplot(mydata, aes(x=b, y=c)) + geom_point()
myplot3 <- ggplot(mydata, aes(x=c, y=d)) + geom_point()
myplot4 <- ggplot(mydata, aes(x=d, y=a)) + geom_point()
set corner labels
myplot1 <- arrangeGrob(myplot1, top = textGrob("A", x = unit(0, "npc")
, y = unit(1, "npc"), just=c("left","top"),
gp=gpar(col="black", fontsize=18, fontfamily="Times Roman")))
myplot2 <- arrangeGrob(myplot2, top = textGrob("B", x = unit(0, "npc")
, y = unit(1, "npc"), just=c("left","top"),
gp=gpar(col="black", fontsize=18, fontfamily="Times Roman")))
myplot3 <- arrangeGrob(myplot3, top = textGrob("C", x = unit(0, "npc")
, y = unit(1, "npc"), just=c("left","top"),
gp=gpar(col="black", fontsize=18, fontfamily="Times Roman")))
myplot4 <- arrangeGrob(myplot4, top = textGrob("D", x = unit(0, "npc")
, y = unit(1, "npc"), just=c("left","top"),
gp=gpar(col="black", fontsize=18, fontfamily="Times Roman")))
plotting all plots on one page
grid.arrange(myplot1, myplot2, myplot3, myplot4, ncol = 2)
An example:
d <- data.frame(x = runif(16),
y = runif(16),
grp = rep(letters[1:4],each = 4))
ggplot(d,aes(x = x,y = y)) +
facet_wrap(~grp) +
geom_point() +
theme(strip.text = element_text(hjust = -0.05),
strip.background = element_blank())
Here's a solution using a custom labeller function. This doesn't invovle any manipulations to the data. Currently it only works with 1-dimensional facets (facet_wrap). I'm still working on how to increment along a 2-D grid...
Define the labeller function
make_labelstring <- function(mypanels) {
mylabels <- sapply(mypanels,
function(x) {LETTERS[which(mypanels == x)]})
return(mylabels)
}
label_panels <- ggplot2::as_labeller(make_labelstring)
Pass label_panels as the labeller to facet_wrap
library(ggplot2)
data("diamonds")
# create a faceted plot
ggplot(data = diamonds, aes(x = depth, y = price)) +
geom_point() +
facet_wrap(~cut, labeller = label_panels) +
theme(strip.text = element_text(hjust = -0),
strip.background = element_blank())

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