Creating Customizable Stacked Grouped Barplots with ggplot
Stacked grouped barplots are a powerful visualization tool for comparing categorical data across different groups. In this article, we’ll explore how to create customizable stacked grouped barplots using the ggplot2 package in R.
Introduction to ggplot2
ggplot2 is a powerful data visualization library based on the Grammar of Graphics. It provides a consistent and expressive syntax for creating complex graphics. The library uses a layer-based approach, where each layer builds upon the previous one, allowing for a high degree of customization.
Creating Stacked Grouped Barplots with ggplot
To create a stacked grouped barplot using ggplot2, we need to follow several steps:
Step 1: Load the Data
The first step is to load our data into R. In this example, we have a data frame called data that contains the following columns:
facet: a categorical variable representing the facet labelsgroup: a categorical variable representing the group labelsstack: a categorical variable representing the stack labelsvalue: a numeric variable representing the values to be plotted
# Load the required libraries
library(ggplot2)
# Create example data frame
set.seed(687532)
data <- data.frame(facet = rep(LETTERS[1:5], each = 6),
group = c("x", "y"),
stack = letters[1:3],
value = round(abs(rnorm(30)), 2))
Step 2: Draw the Barplot with Grouping and Stacking
To create the barplot, we use the ggplot function to specify our data frame as the input. We then use the aes function to map our variables to the aesthetics of the plot.
# Create the stacked grouped barplot
ggplot(data,
aes(x = group,
y = value,
fill = stack)) +
geom_bar(stat = "identity",
position = "stack", width = 0.6) +
theme_classic() +
theme(panel.border = element_rect(colour = NA, fill=NA, size=0),
text = element_text(size = 8, family = "sans")) +
scale_y_continuous(expand = c(0,0)) +
labs(x = "", y = expression(paste("Relative Abundance(%)"))) +
facet_wrap(~facet, strip.position = "bottom", scales = "free_x") +
theme(panel.background = element_blank(),
panel.spacing = unit(0, "line"),
strip.background = element_blank(),
strip.placement = "outside") +
theme(plot.title.position = 'plot',
plot.title = element_text(hjust = 0.5)) +
theme(axis.text.x = element_text(angle = 90, vjust = 0.5, hjust=1))
This code creates a stacked grouped barplot with the specified facets and colors.
Customizing Colors and Patterns
To change the colors and patterns of the stacked bars, we can use the scale_fill_manual function.
# Create a scale fill manual for the bars
ggplot(data,
aes(x = group,
y = value,
fill = stack)) +
geom_bar(stat = "identity",
position = "stack", width = 0.6) +
theme_classic() +
theme(panel.border = element_rect(colour = NA, fill=NA, size=0),
text = element_text(size = 8, family = "sans")) +
scale_y_continuous(expand = c(0,0)) +
labs(x = "", y = expression(paste("Relative Abundance(%)"))) +
facet_wrap(~facet, strip.position = "bottom", scales = "free_x") +
theme(panel.background = element_blank(),
panel.spacing = unit(0, "line"),
strip.background = element_blank(),
strip.placement = "outside") +
theme(plot.title.position = 'plot',
plot.title = element_text(hjust = 0.5)) +
theme(axis.text.x = element_text(angle = 90, vjust = 0.5, hjust=1)) +
scale_fill_manual(values = c("red", "blue", "green"))
However, this approach will not work as expected if we want to maintain the grouped aspect of the barplot.
Alternative Approach: Using geom_col_pattern and scale_fill_manual
We can use the geom_col_pattern function to create a grouped barplot with patterns. However, it doesn’t provide direct control over colors.
# Create a grouped barplot with patterns
ggplot(data,
aes(x = group,
y = value,
fill = stack)) +
geom_col(position = "stack", width = 0.6) +
theme_classic() +
theme(panel.border = element_rect(colour = NA, fill=NA, size=0),
text = element_text(size = 8, family = "sans")) +
scale_y_continuous(expand = c(0,0)) +
labs(x = "", y = expression(paste("Relative Abundance(%)"))) +
facet_wrap(~facet, strip.position = "bottom", scales = "free_x") +
theme(panel.background = element_blank(),
panel.spacing = unit(0, "line"),
strip.background = element_blank(),
strip.placement = "outside") +
theme(plot.title.position = 'plot',
plot.title = element_text(hjust = 0.5)) +
theme(axis.text.x = element_text(angle = 90, vjust = 0.5, hjust=1)) +
scale_fill_manual(values = c("red", "blue", "green"))
This approach still doesn’t provide the desired result.
Alternative Approach: Using scale_fill_manual with hue Aesthetic
Another approach is to use the hue aesthetic in combination with scale_fill_manual. However, this will not work directly if we want to maintain the grouped aspect of the barplot.
# Create a stacked grouped barplot with colors using hue aesthetic
ggplot(data,
aes(x = group,
y = value,
fill = stack,
color = facet)) +
geom_bar(stat = "identity",
position = "stack", width = 0.6) +
theme_classic() +
theme(panel.border = element_rect(colour = NA, fill=NA, size=0),
text = element_text(size = 8, family = "sans")) +
scale_y_continuous(expand = c(0,0)) +
labs(x = "", y = expression(paste("Relative Abundance(%)"))) +
facet_wrap(~facet, strip.position = "bottom", scales = "free_x") +
theme(panel.background = element_blank(),
panel.spacing = unit(0, "line"),
strip.background = element_blank(),
strip.placement = "outside") +
theme(plot.title.position = 'plot',
plot.title = element_text(hjust = 0.5)) +
theme(axis.text.x = element_text(angle = 90, vjust = 0.5, hjust=1)) +
scale_color_manual(values = c("red", "blue", "green"))
However, this approach also doesn’t provide the desired result.
Conclusion
Unfortunately, it’s not possible to change the colors and patterns of stacked grouped barplots using ggplot2 without losing the grouped aspect of the bars. The library is designed with a consistent syntax for creating complex graphics, but sometimes this consistency can be a limitation.
To overcome this limitation, we need to explore alternative libraries or approaches that provide more flexibility in customizing our visualizations.
Last modified on 2023-10-03