rsaveimager

Change color in imager and save image


The documentation of imager shows how to specify your own colors in a plot (see here). This is super handy but I seem to be unable to save a modified plot. How can I achieve that?

library(imager); library(dplyr)
cscale <- function(r, g, b) rgb(g, r, b)
plot(boats, colourscale=cscale, rescale=FALSE)

This works fine. But how can I save this plot? This does not work:

boats %>%
  plot(colourscale=cscale, rescale=FALSE) %>%
  save.image("pathtomachine.jpg")

Thanks.


Solution

  • Use the base pipeline of choosing a device and closing it.

    > library(imager)
    > cscale <- function(r, g, b) rgb(g, r, b)
    > dims <- attributes(boats)$dim  ## get dims
    > jpeg('foo.jpg', dims[1], dims[2])  ## open jpg device
    > par(mar=c(0, 0, 0, 0))  ## switch off margins
    > plot(boats, colourscale=cscale, rescale=FALSE)  ## plot
    > dev.off() |> invisible()  ## close jpg device
    
    > grep('foo.jpg', dir(), value=TRUE)  ## check if it's there
    [1] "foo.jpg"
    

    enter image description here