Specify the plot dimensions in pixels?

[krassowski]

I would like to be able to set the size of my figure in pixels rather than inches using options()

IRkernel used to have set_plot_options() function which permitted specifying units because everything was just being passed to PNG call (https://github.com/IRkernel/IRkernel/pull/82/files#diff-d6114b524c43b90f0e7f0b24a0af9f94L10).

Currently we can only change the size using repr.plot.res, repr.plot.width and repr.plot.height. Would it be possible to add repr.plot.unit="in" so that it can be changed to "px"?

This should be pretty straightforward change and remove the inches hard-coded in:

repr/R/repr_recordedplot.r

Lines 93 to 95 in 7b0a098

	Cairo::Cairo(width, height, tf, 'png', pointsize, bg, 'transparent', 'in', res)
	else
	png(tf, width, height, 'in', pointsize, bg, res, antialias = antialias)

I'm happy to create a pull request if this is change is welcome.

[flying-sheep]

How about we simply allow using grid::unit objects for repr.plot.width/height?

[krassowski]

No strong opinion. On one hand it could be more future-proof and flexible, on the other this would be more repetitive (if the user wanted to change both width and height) and require the user to understand what grid::unit is (which would be only problem for the very beginners, I think that R users learn about it quickly).