How can I write R ggplot charts into palantir foundry file system?

Great question! This is answered in the documentation here: https://www.palantir.com/docs/foundry/code-workbook/transforms-unstructured/#example-saving-a-plot-to-a-pdf It is possible to write to an output FileSystem. This can be useful to write non-tabular data formats including images, PDFs, text files, and so on.

Call new.output() to instantiate a TransformOutput. Learn more about the FileSystem API.

You can only write files using TransformOutput in nodes that are saved as datasets. You cannot write files using TransformOutput in the console.

Here is an example with a scatterplot (saved to a PDF to maintain good resolution):

plot_pdf <- function() {
    library(ggplot2)
    theme_set(theme_bw())  # pre-set the bw theme
    data("midwest", package = "ggplot2")

    # Scatterplot
    gg <- ggplot(midwest, aes(x=area, y=poptotal)) + 
        geom_point(aes(col=state, size=popdensity)) + 
        geom_smooth(method="loess", se=F) + 
        xlim(c(0, 0.1)) + 
        ylim(c(0, 500000)) + 
        labs(subtitle="Area Vs Population", 
            y="Population", 
            x="Area", 
            title="Scatterplot", 
            caption = "Source: midwest")
            
    output <- new.output()
    output_fs <- output$fileSystem()
    pdf(output_fs$get_path("my pdf example.pdf", 'w'))
    plot(gg)
}