Reset Par to the Default Values at Startup

Reset par to the default values at startup

Every time a new device is opened par() will reset, so another option is simply do dev.off() and continue.

Reset the graphical parameters back to default values without use of dev.off()

See ?par. The idea is that you save them as they are when you found them, and then restore:

old.par <- par(mar = c(0, 0, 0, 0))
## do plotting stuff with new settings

Now restore as they were before we changed mar:

par(old.par)

after par(fig), mtext is slightly off

op4 does not have a usr element. After the small inset plot, usr is changed. To reset, something like this can be used:

dev.off()
plot(1:10)
usr <- par("usr")
op4 <- par(fig=c(0.1,0.8,0.3,0.8), new=TRUE)
plot(rnorm(400), type="l")
par(op4)
par(usr=usr)
mtext("hello", adj=1, col=4); mtext("hello", adj=0, col=4)

Fixing RStudio's default par() settings

If the plot window in RStudio is too small, you will get this error.

Keeping that in mind, two options to try are:

1. Enlarge the plot window :-)
2. Try plotting with the standard graphics device (which I believe should be x11() for you).

Changing par() settings to default when plotting rasters

The plot method for raster objects redefines mfrow depending on the number of layers the raster has.

Your raster image has three layers (one for each band: red, green, and blue), as seen here:

r1

## class       : RasterStack 
## dimensions  : 77, 101, 7777, 3  (nrow, ncol, ncell, nlayers)
## resolution  : 1, 1  (x, y)
## extent      : 0, 101, 0, 77  (xmin, xmax, ymin, ymax)
## coord. ref. : +proj=merc 
## names       : red, green, blue 
## min values  :   0,     0,    0 
## max values  : 255,   255,  255 

As a result, when plotted, mfrow is set to c(2, 2) to accommodate the three layers.

Take a look at getMethod('plot', 'Raster') to see what's going on behind the scenes. Here's part of it:

...
if (nl > 1) {
      if (missing(nc)) {
        nc <- ceiling(sqrt(nl))
      }
      else {
        nc <- max(1, min(nl, round(nc)))
      }
      if (missing(nr)) {
        nr <- ceiling(nl/nc)
      }
      else {
        nr <- max(1, min(nl, round(nr)))
        nc <- ceiling(nl/nr)
      }
      old.par <- par(no.readonly = TRUE)
      on.exit(par(old.par))
      par(mfrow = c(nr, nc), mar = c(4, 4, 2, 2))
...

If you wanted to plot just a single band (layer), or two of them, you could use the following, in which case mfrow will be set to c(1, 1) or c(1, 2), respectively:

plot(r1[[3]])   # third band; equivalently, plot(r1, 3)
plot(r1[[1:2]]) # bands 1 and 2; equivalently, plot(r1, 1:2)

As noted by @RobertH, you can modify the layout with the nc argument to the plot method, e.g. plot(r1, nc=1) will give you a single column of three plots.

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In contrast, raster::plotRGB plots such RGB raster objects as a single RGB image.

How to reset par(mfrow) in R

You can reset the mfrow parameter

par(mfrow=c(1,1))

How do I reset all options() arguments to their default values?

If you restart your R session, it will reset the options to the default values.
Options are saved in a list, and calling options() will show that list.

You can save the default options after restarting R:

backup_options <- options()

You can make any changes you need, and then to revert to the default options:

options(backup_options)

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