CODEWITHSUNDEEP
rpngplot
djq
djq

Reputation: 15298

Understanding png output settings

I don't understand how I can arrange a plot to fill an image of a certain pixel size, with a specific font-size and a small margin. Here is an example plot:

library(ggplot2)

a <-c(1:10); b <- c(1:10)
p <- qplot(a,b)
outPath = "D:/Scratch/"

# 1
png(paste(outPath, '1.png', sep=''), height=400, width=400, res = 120, units = 'px')
print(p); dev.off()

enter image description here

# 2
png(paste(outPath, '2.png', sep=''), pointsize = 20,height=400, width=400, res = 120, units = 'px')
print(p); dev.off()

enter image description here

# 3
png(paste(outPath, '3.png', sep=''), height=400, width=400, res = 250, units = 'px')
print(p); dev.off()

enter image description here

I'm less concerned about the resolution of the image, but I want the font size to be large, in proportion to the overall image (similar to plot #3). The argument pointsize does not appear to result in any font size changes.I also want the border to be minimized. At the moment, if I use the settings on #3 there is a much larger space around the plot, when compared to the other images. How can I have a plot that has large font, with a small margin?

Upvotes: 2

Views: 2617

Answers (1)

Josh O&#39;Brien
Josh O&#39;Brien

Reputation: 162451

Controlling most aspects of the saved image will be more easily accomplished on the ggplot2 side of things (compared to playing with png() settings).

Within ggplot2, opts() can be used to control both the font size, and the widths of figure margins.

Here's an example:

p <- qplot(a,b) +
opts(plot.margin = unit(rep(0,4), "lines"),
     axis.title.x = theme_text(size=20),
     axis.title.y = theme_text(size=20))

png('1.png', height=400, width=400, res = 120, units = 'px')
print(p); dev.off()

enter image description here

Upvotes: 2

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