How To Join Multiple ggplot2 Plots with cowplot?
Last Updated :
17 Oct, 2021
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In this article, we are going to see how to join multiple ggplot2 plots with cowplot. To join multiple ggplot2 plots, we use the plot_grid() function of the cowplot package of R Language.
Syntax: plot_grid(plot1,plot2,label=<label-vector>, ncol, nrow)
Parameters:
- plot1 and plot2 are plots that need to be joined.
- <label-vector> is a vector that has a collection of labels for plots.
- ncol is the number of columns canvas will be divided in.
- nrow is the number of rows canvas will be divided in.
Example 1: Two basic ggplot2 plots combined using plot_grid() function.
# Create sample data
set.seed(5642)
sample_data1 <- data.frame(
name = c("Geek1","Geek2","Geek3",
"Geek4","Geeek5") ,
value=c(31,12,15,28,45))
sample_data2 <- data.frame(x = rnorm(400))
# Load ggplot2 and cowplot
library("ggplot2")
library("cowplot")
# Create both plot and store in variable
plot1<-ggplot(sample_data1,
aes(x = name, y = value)) +
geom_point(size=4)
plot2<-ggplot(sample_data2, aes(x = x)) +
geom_density(alpha=0.8)
plot_grid(plot1, plot2, labels = c('Plot1', 'Plot2'))
Output:
Example 2: Create a gap between plots using NULL as plot value.
To fix the number of columns we use ncol attribute of plot_grid() function.
# Create sample data
set.seed(5642)
sample_data <- data.frame(
name = c("Geek1","Geek2","Geek3",
"Geek4","Geeek5") ,
value = c(31,12,15,28,45))
# Load ggplot2 and cowplot
library("ggplot2")
library("cowplot")
# Create both plot and store in variable
plot1<-ggplot(sample_data, aes(x=name, y=value)) +
geom_bar(stat = "identity")
plot2<-ggplot(sample_data, aes(x = name, y=value)) +
geom_segment( aes(x=name, xend=name, y=0, yend=value))
plot_grid(plot1,NULL, NULL, plot2, labels = c(
'Plot1','','', 'Plot2'), ncol=2)
Output:
Example 3: Side by Side plot with the shared legend.
To create a plot with a shared legend, we create plots without a legend and create a separate legend and combine them.
# Create sample data
set.seed(5642)
sample_data <- data.frame(name=c("Geek1","Geek2","Geek3",
"Geek4","Geeek5") ,
value=c(31,12,15,28,45))
# Load ggplot2 and cowplot
library("ggplot2")
library("cowplot")
# Create both plot and store in variable without legend
plot1<-ggplot(sample_data, aes(x=name, y=value, fill=name)) +
geom_bar(stat = "identity") +
theme(legend.position = "none")
plot2<-ggplot(sample_data, aes(x = name, y=value, fill=name)) +
geom_point(aes(colour = factor(name)), size = 6)+
theme(legend.position = "none")
# combine both plot using plot_grid()
combined_plot<-plot_grid(plot1, plot2,ncol=2)
# extract legend from plot2
legend <- get_legend(
plot1 +
guides(color = guide_legend(nrow = 1)) +
theme(legend.position = "bottom")
)
# Combine combined plot and legend using plot_grid()
plot_grid(combined_plot, legend,ncol=1,rel_heights = c(1, .1))
Output:
Example 4: Side by Side plot with a shared title
To create a plot with a shared title, we create plots without titles and create a separate title and combine them.
# Create sample data
set.seed(5642)
sample_data <- data.frame(name=c("Geek1","Geek2",
"Geek3","Geek4","Geeek5") ,
value=c(31,12,15,28,45))
# Load ggplot2 and cowplot
library("ggplot2")
library("cowplot")
# Create both plot and store in variable without legend
plot1<-ggplot(sample_data, aes(x=name, y=value, fill=name)) +
geom_bar(stat = "identity") +
theme(legend.position = "none")
plot2<-ggplot(sample_data, aes(x = name, y=value, fill=name)) +
geom_point(aes(colour = factor(name)), size = 6)+
theme(legend.position = "none")
# combine both plot using plot_grid()
combined_plot<-plot_grid(plot1, plot2,ncol=2)
# create title for plot
title <- ggdraw() +
draw_label(
"Two Plots together with shared title",
fontface = 'bold',
x = 0,
hjust = 0,
size = 24,
)
# Combine combined plot and title using plot_grid()
plot_grid(title, combined_plot ,ncol=1,rel_heights = c(0.1, 1))
Output:
