CODEWITHSUNDEEP
rpdf
user321627
user321627

Reputation: 2572

How to match the height and width values in the pdf() function R to pdf resolution values?

I currently have a plot that I would like to save with certain resolution values. I am using the pdf() function in R with:

pdf("my_plot.pdf", height=5, width=10)
plot(....)
dev.off()

From this, I get a pdf which when I use Mac's Info in Finder, it gets:

enter image description here

I am wondering how I can set the height and width parameters in pdf() to obtain match a certain resolution above, such as 811 x 478. Thanks.

Upvotes: 1

Views: 2200

Answers (1)

IRTFM
IRTFM

Reputation: 263411

If height is 811 and width is 478 pixels (although I later decided those were probably reversed) then you could divide those by a typical dpi to get a height and width in inches which is the unit that the pdf device expects:

pdf("my_plot.pdf", height=811/300, width=478/300)
  plot(....)
dev.off()

I'm wondering, however, whether the first number is a height or width? I suspect you may be seeing width as the first value. Let's look at the help page:

?pdf

And look at some examples with Finder and Preview:

I'm looking at small pdf files and seeing that an icon is reported to have a resolution of 128 × 128 in Finder.app and Preview reports that it is 1.78 × 1.78 inches, so it probably was created as a 72 dpi document. The pdf() help page says that pointsize can be used to affect that parameter and defaults to 12 to specify 1/72 inches.

So perhaps you will want:

pdf("my_plot.pdf", width=811/72, height=478/72)

Upvotes: 4

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