R Under development (unstable) (2025-07-22 r88445 ucrt) -- "Unsuffered Consequences"
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> library(grid)
> library(gridSVG)

Attaching package: 'gridSVG'

The following objects are masked from 'package:grid':

    linearGradient, pattern, radialGradient

The following object is masked from 'package:grDevices':

    dev.off

> dev.new(width=6, height=6)
dev.new(): using pdf(file="Rplots12.pdf")
> # Some default settings
> pushViewport(viewport(gp=gpar(col="black", fill=NA)))
> 
> # A plot with overlapping polygons where the overlap needs to be
> # coloured differently
> 
> # Implemented using transparency
> 
> # Some dummy data
> set.seed(1000)
> x <- sort(runif(20, 1, 10))
> y1 <- (x - 5) + rnorm(20)
> y2 <- -(x - 5) + rnorm(20)
> 
> # Some "analysis"
> lm1 <- lm(y1 ~ x)
> lm2 <- lm(y2 ~ x)
> 
> # Some calculated values to plot
> p1 <- predict(lm1, interval="confidence", type="response")
> p2 <- predict(lm2, interval="confidence", type="response")
> 
> pushViewport(plotViewport(c(5, 5, 4, 2)))
> pushViewport(dataViewport(x, c(p1[,2], p2[,2], p1[,3], p2[,3])))
> grid.rect()
> grid.xaxis()
> grid.yaxis()
> grid.points(x, y1)
> grid.points(x, y2, pch=3)
> grid.lines(x, p1[,1], default.units="native")
> grid.lines(x, p1[,2], default.units="native")
> grid.lines(x, p1[,3], default.units="native")
> grid.lines(x, p2[,1], default.units="native")
> grid.lines(x, p2[,2], default.units="native")
> grid.lines(x, p2[,3], default.units="native")
> # overlapping polygons
> grid.polygon(c(x, rev(x)), c(p1[,2], rev(p1[,3])),
+              gp=gpar(fill="red", alpha=0.5),
+              default.units="native")
> grid.polygon(c(x, rev(x)), c(p2[,2], rev(p2[,3])),
+              gp=gpar(fill="green", alpha=0.5),
+              default.units="native")
> 
> 
> popViewport(2)
> 
> popViewport()
> 
> grid.export("transparency.svg")
> dev.off()
null device 
          1 
> 
> proc.time()
   user  system elapsed 
   0.70    0.09    0.78