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Kay Cichini (MSc, Biology), Nature Protection Expert, Tyrol/Austria. I'm author of theBioBucket-Blog, where I share examples for data management, data processing, statistical analysis and report generation using the R-Software. Kay is a DZone MVB and is not an employee of DZone and has posted 28 posts at DZone. You can read more from them at their website. View Full User Profile

Drawing Grids in R

09.23.2012
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Here's an example of how to draw a grid in R and how to fill it.
I did use the grid-package and its functions for displaying species cover values at squares of a recording frame...






library(grid)

dat <- data.frame(x = rep(seq(0, 0.8, 1/5), 5),
                  y = rep(seq(0, 0.8, 1/5), each = 5),
                  val = rnorm(25, 20, 5))

# making relative values (%) to be used for color-gradiation in plot
dat$rel <- 100 * dat$val / max(dat$val)

# creating grey-tones relative to val -
# maximum greytone is relative to the val-maximum
# i use the reciprocal to get darker tones for higher values:
dat$col<-paste("grey", 100 - round(dat$rel, 0), sep = "")

# opening the graphic device and
# setting up a viewport with borders:
grid.newpage()
vp1 <- viewport(x = 0.1, y = 0.1, w = 0.8, h = 0.8, 
                just = c("left", "bottom"), name = "vp1")

# plotting rectangles using x/y positions
grid.rect(x=dat$x,y=dat$y,height=1/5,width=1/5,hjust=0,vjust=0,vp=vp1,
          gp=gpar(col=1, fill=as.character(dat$col)))







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