Really Cool R Graphic

Really cool R Graphic
Recently I needed to make a funky graphic-table combo in R. Here's the challenge - To combine a vertical bar chart and the data table in a single graphic.

As much as I like R, it's graphics systems are mind-bogglingly complex. You have the base graphics system PLUS Lattice, ggplot, iplot, etc. There are way too many graphics systems. I couldn't even figure out which one I should focus on learning.

When in doubt, turn to the appropriate forum. I posted some stuff on the R-Users mailing list and got a fantastic reply from a guy named Marc. View via Nabble.

I was able to take what he sent me, and learn from it. After playing around with it a little, I got the hang of it and I was able to adapt what he sent and use it for my project at work.

Below is the full version of what he sent me. There is further discussion about this here.

Enjoy!


#---------------------------------------------------------
# Create data
MyData <- matrix(c(57.1, 52.3, 13.5, 13.9, 7.9, 8.8, 5.4, 5.6, 16.1, 19.4), nrow = 2) # Note that by using '\n' in the text, the label will be plotted on # two lines. '\n' is a newline character colnames(MyData) <- c("0 occasions", "1-2 Occasions", "3-5 Occasions", "6-9 Occasions", "10 or more\nOccasions") rownames(MyData) <- c("Androscoggin", "Maine") > MyData
0 occasions 1-2 Occasions 3-5 Occasions 6-9 Occasions
Androscoggin 57.1 13.5 7.9 5.4
Maine 52.3 13.9 8.8 5.6
10 or more\nOccasions
Androscoggin 16.1
Maine 19.4


# Set graph margins to make room for labels
# See ?par
par(mar = c(5, 8, 4, 1))


# Set colors
MyCols <- c("black", "grey80") # Set label size MyCex = 0.75 # Set lines for table data MyLines <- 2:3 # do barplot, getting bar midpoints in 'mp' # See ?barplot mp <- barplot(MyData, beside = TRUE, ylim = c(0, 100), yaxt = "n", cex.names = MyCex, col = MyCols) # mp contains the following. The mean of each column # is the horizontal center of each pair of bars > mp
[,1] [,2] [,3] [,4] [,5]
[1,] 1.5 4.5 7.5 10.5 13.5
[2,] 2.5 5.5 8.5 11.5 14.5


# Put a box around it
box()


# Draw y axis tick marks and labels
axis(2, at = seq(0, 100, 10), las = 1)


# Draw values below plot
# Use the values of 'mp' from above.
# See ?mtext
mtext(side = 1, text = MyData,
at = rep(colMeans(mp), each = nrow(MyData)),
line = MyLines, cex = MyCex)


# Get min value for the x axis. See ?par 'usr'
min.x <- par("usr")[1]


# Draw categories using mtext
# See ?strwidth to get the length of the labels in
# user coordinates, which is then used for 'at'
# Setting 'adj = 0' left justifies the text
mtext(side = 1, line = MyLines, text = rownames(MyData),
at = min.x - max(strwidth(rownames(MyData), cex = MyCex)),
adj = 0, cex = MyCex)


# Draw the colored boxes
# Same here for strheight as with strwidth above
# Part of this is getting the vertical positioning to align with
# the text and the horizontal position at the beginning of the labels
# Note that we have to set 'xpd = TRUE' so that the points are drawn
# outside the plotting region. See ?par and 'xpd'
# We just need a single capital letter for strheight() to get the value

VertOff <- strheight("X", cex = MyCex) * c(6, 8)
HorizOff <- min.x - (0.85 * max(strwidth(rownames(MyData))))

points(rep(HorizOff, nrow(MyData)),
par("usr")[3] - VertOff, bg = MyCols, pch = 22,
xpd = TRUE, cex = MyCex)
# --------------------------------------------------------------------------------------------