👀 Views: 441 💬 Answers: 1 📅 Created: 2025-06-14

ggplot2 data-visualization faceting R

I'm upgrading from an older version and I'm building a feature where I'm trying to create a faceted plot using `ggplot2`, but I'm having trouble with customizing the facet labels when using a custom function. I have a dataset where I'm trying to plot the sales data for different products across various regions. I've written a function to generate more descriptive labels based on the product and region names, but the labels don't appear as expected in the facets. Here's a simplified version of the code I've written: ```r library(ggplot2) library(dplyr) # Sample data frame sales_data <- data.frame( product = rep(c('A', 'B', 'C'), each = 10), region = rep(c('North', 'South', 'East', 'West'), times = c(3, 3, 2, 2)), sales = rnorm(30, mean = 100, sd = 10) ) # Custom function for labeling custom_label <- function(product, region) { paste('Sales of', product, 'in', region) } # Facet plot ggplot(sales_data, aes(x = region, y = sales)) + geom_bar(stat = 'identity') + facet_wrap(~ product, labeller = labeller(product = custom_label)) ``` When I run this code, I get the following warning message: ``` Warning: Faceting variables must be factors. ``` I've ensured that both `product` and `region` are factors in my dataset, so I'm not sure what's going wrong. The plot generates, but the labels are just the factor levels instead of the custom labels from my function. I've tried using `as.factor()` on the `product` variable, but this didn't change the outcome. Could someone guide to figure out how to properly use a custom labeller function in `facet_wrap`? Any suggestions would be greatly appreciated! The project is a application built with R. Thanks for your help in advance!