How To Store R Ggplot Graph As Html Code Snippet

I am creating an html document by creating various objects with ggplotly() and htmltools functions like h3() and html(). Then I submit them as a list to htmltools::save_html() to

Solution 1:

If you want to save the plot as a dynamic plotly graph, you could use htmlwidgets::saveWidget. This will produce a stand-alone html file.

Here is a minimal example:

library(tidyverse);
library(plotly);
library(htmlwidgets);

df <- data.frame(x = 1:25, y = c(1:25 * 1:25))
gg <- ggplot(df,aes(x = x, y = y)) + geom_point()

# Save ggplotly as widget in file test.html
saveWidget(ggplotly(gg), file = "test.html");

Solution 2:

I ended up generating a temparory image file, then base64 encoding it, within a function I called encodeGraphic() (borrowing code from LukeA's post):

library(ggplot2)
library(RCurl)
library(htmltools)
encodeGraphic <- function(g) {
  png(tf1 <- tempfile(fileext = ".png"))  # Get an unused filename in the session's temporary directory, and open that file for .png structured output.
  print(g)  # Output a graphic to the file
  dev.off()  # Close the file.
  txt <- RCurl::base64Encode(readBin(tf1, "raw", file.info(tf1)[1, "size"]), "txt")  # Convert the graphic image to a base 64 encoded string.
  myImage <- htmltools::HTML(sprintf('<img src="data:image/png;base64,%s">', txt))  # Save the image as a markdown-friendly html object.
  return(myImage)
}

HTMLOut <- "~/TEST.html"   # Say where to save the html file.
g <- ggplot(mtcars, aes(x=gear,y=mpg,group=factor(am),color=factor(am))) + geom_line()  # Create some ggplot graph object
hg <- encodeGraphic(g)  # run the function that base64 encodes the graph
forHTML <- list(h1("My header"), p("Lead-in text about the graph"), hg)
save_html(forHTML, HTMLOut)  # output it to the html file.

Solution 3:

I think what you want may be close to one of the following:

1. Seems you are creating an HTML report but hasn't checked out RMarkdown. It comes with Base64 encode. When you create an RMarkdown report, pandoc automatically converts any plots into an HTML element within the document, so the report is self-contained.

2. SVG plots. This is less likely to be what you might want, but SVG plots are markup-language based and may be easily portable. Specify .svg extension when you use ggsave() and you should be getting an SVG image. Note that SVG is an as-is implementation of the plot, so if can be huge in file size if you have thousands of shapes and lines.

Solution 4:

This is an extension to the Maurits Evers post. In this answer I'm showing how to combine multiple plotly plots in the same html file in an organized fashion:

library("plotly")
library("htmltools")

# a small helper function to avoid repetition
my_func <- function(..., title){
    ## Description:
    ##   A function to add title to put multiple gg plotly objects under a html heading
    ##
    ## Arguments:
    ##   ...: a list of gg objects
    ##   title: a character vector to specify the heading text
    
    # get the ... in list format
    lst <- list(...)
    
    # create the heading
    tmp_title <- htmltools::h1(title)
    
    # convert each ggplot to ggplotly and put them under the same div html tag
    tmp_plot <- lapply(lst, ggplotly) |>
        htmltools::div()
    
    # return the final object as list
    return(list(tmp_title, tmp_plot))
}

# a toy data
df <- data.frame(x = 1:25, y = c(1:25 * 1:25))

# the ggplot object using the toy data
gg <- ggplot(df,aes(x = x, y = y)) + geom_point()

# put everything in order
final_list <- list(my_func(obj = list(gg, gg, gg), title = "The first heading"),
                   my_func(obj = list(gg, gg), title = "The second heading"))

# write to disk as a unified HTML file
htmltools::save_html(html = final_list,
                     file = "index.html"))

Disclaimer: I specifically did this to avoid using widgetframe R package and to be completely on par with the documentation of plotly-r. You can read the link if you are comfortable with adding extra dependency and extra abstraction layer. I prefer to use packages if and only if necessary. :)