pairs
Scatterplot Matrices
A matrix of scatterplots is produced.
- Keywords
- hplot
Usage
pairs(x, …)# S3 method for formula
pairs(formula, data = NULL, …, subset,
na.action = stats::na.pass)
# S3 method for default
pairs(x, labels, panel = points, …,
horInd = 1:nc, verInd = 1:nc,
lower.panel = panel, upper.panel = panel,
diag.panel = NULL, text.panel = textPanel,
label.pos = 0.5 + has.diag/3, line.main = 3,
cex.labels = NULL, font.labels = 1,
row1attop = TRUE, gap = 1, log = "")
Arguments
- x
the coordinates of points given as numeric columns of a matrix or data frame. Logical and factor columns are converted to numeric in the same way that
data.matrixdoes.- formula
a formula, such as
~ x + y + z. Each term will give a separate variable in the pairs plot, so terms should be numeric vectors. (A response will be interpreted as another variable, but not treated specially, so it is confusing to use one.)- data
a data.frame (or list) from which the variables in
formulashould be taken.- subset
an optional vector specifying a subset of observations to be used for plotting.
- na.action
a function which indicates what should happen when the data contain
NAs. The default is to pass missing values on to the panel functions, butna.action = na.omitwill cause cases with missing values in any of the variables to be omitted entirely.- labels
the names of the variables.
- panel
function(x, y, …)which is used to plot the contents of each panel of the display.- …
arguments to be passed to or from methods.
Also, graphical parameters can be given as can arguments to
plotsuch asmain.par("oma")will be set appropriately unless specified.- horInd, verInd
The (numerical) indices of the variables to be plotted on the horizontal and vertical axes respectively.
- lower.panel, upper.panel
separate panel functions (or
NULL) to be used below and above the diagonal respectively.- diag.panel
optional
function(x, …)to be applied on the diagonals.- text.panel
optional
function(x, y, labels, cex, font, …)to be applied on the diagonals.- label.pos
yposition of labels in the text panel.- line.main
if
mainis specified,line.maingives thelineargument tomtext()which draws the title. You may want to specifyomawhen changingline.main.- cex.labels, font.labels
graphics parameters for the text panel.
- row1attop
logical. Should the layout be matrix-like with row 1 at the top, or graph-like with row 1 at the bottom?
- gap
distance between subplots, in margin lines.
- log
a character string indicating if logarithmic axes are to be used: see
plot.default.log = "xy"specifies logarithmic axes for all variables.
Details
The \(ij\)th scatterplot contains x[,i] plotted against
x[,j]. The scatterplot can be customised by setting panel
functions to appear as something completely different. The
off-diagonal panel functions are passed the appropriate columns of
x as x and y: the diagonal panel function (if
any) is passed a single column, and the text.panel function is
passed a single (x, y) location and the column name.
Setting some of these panel functions to NULL is
equivalent to not drawing anything there.
The graphical parameters pch and col can be used
to specify a vector of plotting symbols and colors to be used in the
plots.
The graphical parameter oma will be set by
pairs.default unless supplied as an argument.
A panel function should not attempt to start a new plot, but just plot
within a given coordinate system: thus plot and boxplot
are not panel functions.
By default, missing values are passed to the panel functions and will
often be ignored within a panel. However, for the formula method and
na.action = na.omit, all cases which contain a missing values for
any of the variables are omitted completely (including when the scales
are selected).
Arguments horInd and verInd were introduced in R
3.2.0. If given the same value they can be used to select or re-order
variables: with different ranges of consecutive values they can be
used to plot rectangular windows of a full pairs plot; in the latter
case ‘diagonal’ refers to the diagonal of the full plot.
References
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
Examples
library(graphics)
# NOT RUN {
pairs(iris[1:4], main = "Anderson's Iris Data -- 3 species",
pch = 21, bg = c("red", "green3", "blue")[unclass(iris$Species)])
## formula method
pairs(~ Fertility + Education + Catholic, data = swiss,
subset = Education < 20, main = "Swiss data, Education < 20")
pairs(USJudgeRatings)
## show only lower triangle (and suppress labeling for whatever reason):
pairs(USJudgeRatings, text.panel = NULL, upper.panel = NULL)
## put histograms on the diagonal
panel.hist <- function(x, ...)
{
usr <- par("usr"); on.exit(par(usr))
par(usr = c(usr[1:2], 0, 1.5) )
h <- hist(x, plot = FALSE)
breaks <- h$breaks; nB <- length(breaks)
y <- h$counts; y <- y/max(y)
rect(breaks[-nB], 0, breaks[-1], y, col = "cyan", ...)
}
pairs(USJudgeRatings[1:5], panel = panel.smooth,
cex = 1.5, pch = 24, bg = "light blue",
diag.panel = panel.hist, cex.labels = 2, font.labels = 2)
## put (absolute) correlations on the upper panels,
## with size proportional to the correlations.
panel.cor <- function(x, y, digits = 2, prefix = "", cex.cor, ...)
{
usr <- par("usr"); on.exit(par(usr))
par(usr = c(0, 1, 0, 1))
r <- abs(cor(x, y))
txt <- format(c(r, 0.123456789), digits = digits)[1]
txt <- paste0(prefix, txt)
if(missing(cex.cor)) cex.cor <- 0.8/strwidth(txt)
text(0.5, 0.5, txt, cex = cex.cor * r)
}
pairs(USJudgeRatings, lower.panel = panel.smooth, upper.panel = panel.cor)
pairs(iris[-5], log = "xy") # plot all variables on log scale
pairs(iris, log = 1:4, # log the first four
main = "Lengths and Widths in [log]", line.main=1.5, oma=c(2,2,3,2))
# }