Cannot insert plot into XLSX via openxlsx package when using command line

Question

I'm trying to insert a plot into an XLSX file using the openxlsx package in R. When I use the R GUI, I am able to accomplish this.

However, when using a batch file, the plot is created but it is not inserted into the XLSX file. Instead, it is created as a separate PDF file adjacent to the newly created XLSX file (automatically named "Rplots.pdf"). The data frame is written into the XLSX file just fine.

The R script (named "insertPlot.R"):

library(ggplot2)
library(openxlsx)
wb <- createWorkbook()
addWorksheet(wb, "Data")
addWorksheet(wb, "Graph", gridLines=FALSE)
df <- data.frame(c(1:5), c(5:1))
names(df) <- c("x","y")
writeData(wb, "Data", df)
p <- ggplot(aes(x=x, y=y), data=df) + geom_line(size=1, colour="blue")
print(p)    #plot needs to be showing
insertPlot(wb, "Graph", width=11.18, height=7.82, fileType="png", units="in")
saveWorkbook(wb, "test.xlsx", overwrite=TRUE)

The batch file script:

"C:\Program Files\R\R-3.1.3\bin\RScript.exe" --no-save --no-environ --no-init-file --no-restore --no-Rconsole "C:\temp\insertPlot.R"

In summary, I'm confused as to how to have an RScript batch file accomplish this.

Has anyone had any success or can point out my mistake?

Answer 1

I believe I have found a way to seamlessly accomplish this by outputting the plot to a png device and then utilizing insertImage from the openxlsx package.

library(ggplot2)
library(openxlsx)

wb <- createWorkbook()
addWorksheet(wb, "Data")
addWorksheet(wb, "Graph", gridLines=FALSE)

df <- data.frame(c(1:5), c(5:1))
names(df) <- c("x","y")
writeData(wb, "Data", df)

png("graph.png", width=1024, height=768, units="px", res=144)  #output to png device
p <- ggplot(aes(x=x, y=y), data=df) + geom_line(size=1, colour="blue")
print(p)
dev.off()  #important to shut down the active png device
insertImage(wb, "Graph", "graph.png", width=11.18, height=7.82, units="in")

saveWorkbook(wb, "test.xlsx", overwrite=TRUE)

#unlink("graph.png")  #can optionally delete the original png file

Hope this helps anyone that could be facing the same issue.