Basic code
pdf("mygraph.pdf")
attach(mtcars)
plot(wt, mpg)
abline(lm(mpg ~ wt))
title("Regression of MPG on Weight")
detach(mtcars)
x <- c(1:10)
y <- x
lines(x, y, type="b", pch=22, col="blue", lty=2)
dev.off()
|
Variations include win.metafile(), png(), jpeg(), bmp(), tiff(), xfig(), postscript()
Other functions include dev.new(), dev.next(), dev.prev(), dev.set()
Graphical parameters
par(optionname=value, optionname=value, ...)
opar <- par(no.readonly=TRUE)
par(lty=2, pch=17)
plot(dose, drugA, type="b")
# type - "b": both points and lines, "l": lines, "p": points, "c": lines part of "b", "n": no plotting, "o": both "overplotted"
par(opar)
|
Symbols and lines
|
Specifies the symbol to use when plotting points |
|
Specifies the symbol size. A number indicating the amount plotting symbols are scaled relative to default. 1=default, 1.5 is 50% larger, 0.5 is 50% smaller, and so forth. |
|
Specifies the line type |
|
Specifies the line width. Expressed relative to default (=1), e.g. lwd=2
- a line twice as wide as the default |
Color parameters
|
Default plotting color. Some functions (e.g. lines and pie) accept a vector of values that are recycled. |
|
Color for axis text |
|
Color for axis labels |
|
Color for titles |
|
Color for subtitles |
|
The plot's foreground color |
|
The plot's background color |
|
Produces # contiguous "rainbow" colors |
|
Specify gray levels as a vector of numbers between 0 and 1. This produces 10 gray levels. |
Text parameters
|
Number indicating the amount by which plotted text should be scaled relative to the default |
|
Magnification of axis text relative to cex
|
|
Magnification of axis labels relative to cex
|
|
Magnification of titles relative to cex
|
|
Magnification of subtitles relative to cex
|
|
|
Font parameters
|
Integer specifying font to use for plotted text. 1=plain, 2=bold, 3 =italic, 4=bold italic, 5=symbol (Adobe symbol encoding) |
|
Font for axis text |
|
Font for axis labels |
|
Font for titles |
|
Font for subtitles |
|
Font point size (roughly 1/72 inch). The text size = ps*cex. |
|
Font family for drawing text. Standard values are serif
, sans
, and mono
. |
Mapping for font family created via windowsFont() function.
For Mac, use quartzFonts().
windowsFonts(
A=windowsFont("Arial Black"),
B=windowsFont("Bookman Old Style"),
C=windowsFont("Comic Sans MS")
)
Graph and margin parameters
|
Plot dimensions (width, height) in inches |
|
Numerical vector indicating margin size, c(bottom,left,top,right). Expressed in inches |
|
Numerical vector indicating margin size, c(bottom,left,top,right). Expressed in lines. The default is c(5,4,4,2) + 0.1. |
Example code
dose <- c(20,30,40,45,60)
drugA <- c(16,20,27,40,60)
drugB <- c(15,18,25,31,40)
opar <- par(no.readonly=TRUE)
par(pin=c(2,3))
par(lwd=2, cex=1.5)
par(cex.axis=.75, font.axis=3)
plot(dose, drugA, type="b", pch=19, lty=2, col="red")
lines(dose, drugB, type="b", pch=23, lty=6, col="blue", bg="green")
par(opar)
|
Graph text and customization
|
Using in plot() statement or par() statement remove default titles and labels |
|
title(main="main title", col.main="red", sub="sub-title", col.sub="blue", xlab="x-axis label", ylab="y-axis label", col.lab="green", cex.lab=0.75)
|
|
Create custom axes. When creating a custom axis, suppress axis by using option axes=FALSE
(suppresses all axes, including axis frame lines, unless frame.plot=TRUE
), xaxt="n"
or yaxt="n"
. See Axis options. |
|
Add text within graph, typically labeling points or text annotations, e.g. text(location, "text", pos, ...)
|
|
Add text to margin of plot |
| |
e.g. mtext("text", side=4, line=3, cex.lab=1, las=2, col="blue")
|
|
Add mathematical symbols and formulas to graph |
|
Add reference lines to graph e.g. abline(h=yvalues, v=xvalues)
|
| |
abline(h=c(1,5,7)
adds horizontal lines at y=1, 5 & 7 |
legend(location, title, legend, ...)
|
location - (x,y) coordinate, locator(1), keywords, i.e. bottom, bottomleft, left, topleft, top, topright, right, bottomright, center
. Use inset=
to specify amount to move legend into graph as fraction of plot region. |
| |
title - character string for the legend title (optional) |
| |
legend - character vector with the labels |
| |
... - Other options: col=
, pch=
, lwd=
, lty=
, fill=
, bty=
, bg=
, cex=
, text.col=
, horiz=TRUE
|
|
|
Example code
attach(mtcars)
plot(wt, mpg, main="Mileage vs. Car Weight", xlab="Weight", ylab="Mileage", pch=18, col="blue")
text(wt, mpg, row.names(mtcars), cex=0.6, pos=4, col="red")
detach(mtcars)
|
Combining graphs
Used in par()
or layout()
function:
mfrow=c(nrows, ncols)
- fill by row
mfcol=c(nrows, ncols)
- fill by column
layout(mat)
where mat
is matrix object specifying location of multiple plots to combine
e.g. layout(matrix(c(1,1,2,3), 2, 2, byrow = TRUE))
- one figure placed in row 1 and two figures placed in row 2
Optional parameters for layout()
:
widths()
- a vector of values for widths of columns
heights()
- a vector of values for heights of rows
e.g. layout(matrix(c(1, 1, 2, 3), 2, 2, byrow = TRUE), widths=c(3, 1), heights=c(1, 2))
Used in par()
function:
fig=c(x1, x2, y1, y2), new = TRUE
- Plot within limits of (x1,x2) and (y1,y2), new = TRUE
option adds figure to existing graph |
Axis options
|
An integer indicating the side of the graph to draw the axis (1=bottom, 2=left, 3=top, 4=right) |
|
A numeric vector indicating where tick marks should be drawn |
|
A character vector of labels to be placed at the tick marks (if NULL
, the at
values will be used) |
|
The coordinate at which the axis line is to be drawn (i.e. the value on the other axis where it crosses) |
|
Line type |
|
The line and tick mark color |
|
Labels are parallel (=0) or perpendicular (=2) to the axis |
|
Length of tick mark as a fraction of the plotting region (a '-' number is outside the graph, a '+' number is inside, 0 suppresses ticks, 1 creates gridlines). Default is -0.01. |
Adding minor tick marks require Hmisc package.
library(Hmisc)
minor.tick(nx=n, ny=n, tick.ratio=n)
where nx, ny are no. of intervals to divide major tick marks on x- and y-axis, tick.ratio is size of minor relative to major tick mark
|
