How to create a Sankey plot in R?, You must install the ggsankey library and modify your dataset using the package’s make_long function in order to produce a Sankey diagram in ggplot2.
The data’s columns must correspond to the stages x (current stage), next_x (next stage), node (current node), and next_node (the following node).
Keep in mind that the final stage should indicate a NA.
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Let’s install the remotes packages first,
install.packages("remotes")
Now we can install ggsankey package
remotes::install_github("davidsjoberg/ggsankey")
library(ggsankey)
Load Data
We can make use of mtcars data sets in R.
df <- mtcars %>% make_long(cyl, vs, am, gear, carb) df
x node next_x next_node 1 cyl 6 vs 0 2 vs 0 am 1 3 am 1 gear 4 4 gear 4 carb 4 5 carb 4 <NA> NA 6 cyl 6 vs 0
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Sankey plot with ggsankey
To construct Sankey diagrams in ggplot2, the ggsankey package includes a geom called geom_sankey.
Keep in mind that you must give a factor as the fill colour when passing the variables to aes. The theme theme_sankey is also present in the function.
Let’s load ggplot2 for graph generation
library(ggplot2) library(dplyr)
ggplot(df, aes(x = x, next_x = next_x, node = node, next_node = next_node, fill = factor(node))) + geom_sankey() + theme_sankey(base_size = 16)
How to add labels in Sankey Plot
The package’s geom_sankey_label function lets you add labels to Sankey diagrams.
Remember to give the variable you want to display as the label inside the aes.
ggplot(df, aes(x = x, next_x = next_x, node = node, next_node = next_node, fill = factor(node), label = node)) + geom_sankey() + geom_sankey_label() + theme_sankey(base_size = 16)
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How to do Color customization in Sankey Plot
To alter how the Sankey diagram appears in R, a variety of arguments can be changed. The author of the program produced the following pictures as examples.
geom_sankey aesthetics geom_sankey geometries Color and fill of the Sankey plot
For instance, by adjusting the fill color palette and a few of the inputs to the geom_sankey_function, we can produce something like this.
ggplot(df, aes(x = x, next_x = next_x, node = node, next_node = next_node, fill = factor(node), label = node)) + geom_sankey(flow.alpha = 0.5, node.color = 1) + geom_sankey_label(size = 3.5, color = 1, fill = "white") + scale_fill_viridis_d(option = "A", alpha = 0.95) + theme_sankey(base_size = 16)
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Changing the title of the legend
Changes to the legend’s title are available, just like with other ggplot2 charts. Here are several options for action.
ggplot(df, aes(x = x, next_x = next_x, node = node, next_node = next_node, fill = factor(node), label = node)) + geom_sankey(flow.alpha = 0.5, node.color = 1) + geom_sankey_label(size = 3.5, color = 1, fill = "white") + scale_fill_viridis_d() + theme_sankey(base_size = 16) + guides(fill = guide_legend(title = "Title"))
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Removing the legend
Finally, you can adjust the Sankey plot legend’s position to “none” if you want to remove it.
ggplot(df, aes(x = x, next_x = next_x, node = node, next_node = next_node, fill = factor(node), label = node)) + geom_sankey(flow.alpha = 0.5, node.color = 1) + geom_sankey_label(size = 3.5, color = 1, fill = "white") + scale_fill_viridis_d() + theme_sankey(base_size = 16) + theme(legend.position = "none")
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