plot-barplot-2.R
In rockchalk: Regression Estimation and Presentation

## Title: plot-barplot-1
## Author: Paul Johnson <pauljohn at ku.edu>
## Date posted: 2011
## Description. barplot label customization

### Paul Johnson
### Twisting the margins of a barplot

### I never thought too much about customizing barplots, but
### now I have learned some tricks to share.  Step through these
### examples to see the possibilities.

set.seed(424242)

x <- rpois(10, lambda = 10)

mynames <- c(rep("Really Long Name", 9), "Really Long Name Long Long")


#RSiteSearch("barplot names margins")


barplot(x)


### Note long names off edge:
barplot(x, names = mynames, las = 2)

### Abbreviate offers one solution
barplot(x, names = abbreviate(mynames), las = 2)

### Other option is to reset margins
###default mar is c(5.1, 4.1, 4.1, 2.1)

### Lets make the bottom margin larger
par(mar = c(15, 4.1, 4.1, 2.1))
barplot(x, names = mynames, las = 2)



### Now the bottom is finished. But I'd like a legend.

legend("topleft", legend = c("A really long label", "B", "Cee What I can do?", "D"), col = 1:2)

### My bar hits the legend. How to fix?


### It is not sufficient to simply "move the legend" up
### because then it runs off the edge of the graph
barplot(x, names = mynames, las = 2)
legend(2, 22, legend = c("A really long label", "B", "Cee What I can do?", "D"), col = 1:2)

### By itself, changing the top margin does not help.
### It is also vital to set the xpd parameter to T so that
### R will draw outside the main plot region
par(mar = c(10, 4.1, 8.1, 2.1))
par(xpd = T)
barplot(x, names = mynames, las = 2)
legend(2, 22, legend = c("A really long label", "B", "Cee What I can do?", "D"), col = 1:2)


### Now lets gain some control on the colors and bars
### The default colors are so dark.  You can't write on top
### of them.  You can grab shades of gray like "gray30" or such.

### I'll just specify 4 colors I know will work. I prefer
### the light gray colors because they can be written over.
mycols <- c("lightgray", "gray70", "gray80", "gray90", "gray75")

barplot(x, names = mynames, las = 2, col = mycols)

legend(2, 20, legend = c("A", "B", "C", "D"), fill = mycols)

### Still, I don't like the solid shades so much.
### fill up the bars with angled lines.
### density determines number of lines inside the bar.

myden <- c(60, 20, 30, 40, 25)
### angles determines the direction of lines inside bars
myangles <- c(20, -30, 60, -40, 10)

barplot(x, names = mynames, las = 2, col = mycols, density = myden, angle = c(20, 60, -20))

legend(1, 20, legend = c("A", "B", "C", "D"), density = myden, angle = myangles)

### for my coupe de grace, lets do some writing in the bars.

### Recall from Verzani you can get the x coordinates from the barplot
barPositions <- barplot(x, names = mynames, las = 2, col = mycols, density = myden, angle = c(20, 60, -20))

barPositions

### The text option srt = 90 turns the text sideways

### I'm just guessing that bars 1 and 8 should be labeled
### at coordinates 5 and 5

text (barPositions[1], 5, "my first bar is great", srt = 90)

text (barPositions[8], 5, "but 8 is greater", srt = 90)

### Recently I had the problem of drawing a "clustered" bar chart.
### Lets suppose our x variable really represents responses from
### 2 groups of respondents, Men and Women.

## Create the matrix
xmatr <- matrix(x, nrow = 5)

### Use beside = T to cause barplot to treat each column
### of values as a group
barplot(xmatr, beside = TRUE, names = c("Men", "Women"))

valueNames <- c("Very Strong", "Somewhat Strong", "Not Strong", "Somewhat Weak", "Very Weak")

### Use mtext to write in the margin so that labels on plot are nice.

par(mar = c(10, 4.1, 5.1, 2.1))

bp <- barplot(xmatr, beside = TRUE, names = NULL)

### bp contains the positions of the bars.
mtext(valueNames, side = 1, las = 3, at = bp)

mtext(c("Men", "Women"), side = 1, at = c(bp[3], bp[8]), line = 8, cex = 2)

### Adding numbers to the bars may clarify
text ( bp, as.vector(xmatr), labels = as.vector(xmatr), pos = 1)

### However, the default color is too dark.

### Retrieve the first 5 items from the default grey color scale

gc <- grey.colors(5)

### Replace the first one with a lighter gray

gc[1] <- "gray80"

bp <- barplot(xmatr, beside = TRUE, names = NULL, col = gc)

### bp contains the positions of the bars.
mtext(valueNames, side = 1, las = 3, at = bp)

mtext(c("Men", "Women"), side = 1, at = c(bp[3], bp[8]), line = 8, cex = 2)

### Adding numbers to the bars may clarify
text ( bp, as.vector(xmatr), labels = as.vector(xmatr), pos = 1)

### That's OK for me.  I wonder if I might not just write inside the
### bars. Hmmm.


bp <- barplot(xmatr, beside = TRUE, names = c("Men", "Women"), col = gc)

text(bp, 0.5*as.vector(xmatr), valueNames, srt = 90)

### Hm. That's OK, but maybe I'd pref uniform vertical
### placement of text.

bp <- barplot(xmatr, beside = TRUE, names = c("Men", "Women"), col = gc)

text(bp, 2, valueNames, srt = 90, pos = 4)

### Hell, now the text is aligned vertically, but not centered
### in the bar. I can't figure out all of the details concerning
###

### I'm not able to say for sure what the best fix might be.
### I can either manipulate the x placement like so

bp <- barplot(xmatr, beside = TRUE, names = c("Men", "Women"), col = gc)
text(bp-0.25, 2, valueNames, srt = 90, pos = 4)

### Or use the offset option in the text command.
### I do not understand why this particular value works.

bp <- barplot(xmatr, beside = TRUE, names = c("Men", "Women"), col = gc)
text(bp, 2, valueNames, srt = 90, pos = 4, offset = -0.15)


### Don't forget: When save this into a file, the graph
### may be re-sized and text might "overflow" the boxes.
### That's especially likely if you have a large graph
### on the screen and then try to save the file with
### dev.copy(postscript...)
### That will resize some things, but not all.

### Here is the way to protect yourself.  Resize your "screen" device
### so that it is the same size--in inches--as the output file.

### On linux, I run

x11( width = 6, height = 6 )

### On windows, I think it is windows( width = 6, height = 6 )

### After you do that, run the par command again. The par command
### has to be executed again each time a device is created. That applies to
### the most recently created device.

p <- barplot(xmatr, beside = TRUE, names = c("Men", "Women"), col = gc)
text(bp-0.25, 2, valueNames, srt = 90, pos = 4)

### If that looks OK, then do this


postscript(file = "mybar-1.eps", height = 6, width = 6, onefile = F, horizontal = F, paper = "special", family = "Times")
p <- barplot(xmatr, beside = TRUE, names = c("Men", "Women"), col = gc)
text(bp-0.25, 2, valueNames, srt = 90, pos = 4)
dev.off()


### note that the par settings have shifted back to the defaults.
### Each device is separate.
### As a result, the barplot we created before with large margins would
### make a horrible plot if you forgot to insert the par() commands here:


postscript(file = "mybar-2.eps", height = 6, width = 6, onefile = F, horizontal = F, paper = "special", family = "Times")
par(mar = c(10, 4.1, 5.1, 2.1))


bp <- barplot(xmatr, beside = TRUE, names = NULL, col = gc)

### bp contains the positions of the bars.
mtext(valueNames, side = 1, las = 3, at = bp)

mtext(c("Men", "Women"), side = 1, at = c(bp[3], bp[8]), line = 8, cex = 2)

### Adding numbers to the bars may clarify
text ( bp, as.vector(xmatr), labels = as.vector(xmatr), pos = 1)
dev.off()


### Finally, suppose you make a mistake of specifying your
### output device size too small. The graph I made before
### with the text in the bars looked good on the screen,
### but it looks bad in a smaller output device. The text
### does not match the bars in this example.

postscript(file = "mybar-4.eps", height = 4, width = 4, onefile = F, horizontal = F, paper = "special", family = "Times")
bp <- barplot(xmatr, beside = TRUE, names = c("Men", "Women"), col = gc)
text(bp-0.25, 2, valueNames, srt = 90, pos = 4)
dev.off()