plot.PCA: Draw the Principal Component Analysis (PCA) graphs

Description

Plot the graphs for a Principal Component Analysis (PCA) with supplementary individuals, supplementary quantitative variables and supplementary categorical variables.

Usage

"plot"(x, axes = c(1, 2), choix = c("ind","var","varcor"), ellipse = NULL, xlim = NULL, ylim = NULL, habillage="none",  col.hab = NULL, col.ind="black", col.ind.sup="blue",  col.quali="magenta", col.quanti.sup="blue", col.var="black", label = c("all","none","ind","ind.sup","quali","var","quanti.sup"),
	invisible = c("none","ind","ind.sup","quali","var","quanti.sup"),  lim.cos2.var = 0., title = NULL, palette=NULL, autoLab = c("auto","yes","no"), new.plot = FALSE, select = NULL, 
	unselect = 0.7, shadowtext = FALSE, legend = list(bty = "y", x = "topleft"),
	...)

Arguments

an object of class PCA

axes

a length 2 vector specifying the components to plot

choix

the graph to plot ("ind" for the individuals, "var" for the variables, "varcor" for a graph with the correlation circle when scale.unit=FALSE)

ellipse

boolean (NULL by default), if not null, draw ellipses around the individuals, and use the results of coord.ellipse

xlim

range for the plotted 'x' values, defaulting to the range of the finite values of 'x'

ylim

range for the plotted 'y' values, defaulting to the range of the finite values of 'y'

habillage

give no color for the individuals ("none"), a color for each individual ("ind"), or color the individuals among a categorical variable (give the number of the categorical variable)

col.hab

a vector with the color to use for the individuals

col.ind

a color for the individuals only if there is not habillage

col.ind.sup

a color for the supplementary individuals only if there is not habillage

col.quali

a color for the categories of categorical variables only if there is not habillage

col.quanti.sup

a color for the quantitative supplementary variables

col.var

a color for the variables

label

a list of character for the elements which are labelled (by default, all the elements are labelled ("ind", ind.sup", "quali", "var", "quanti.sup"))

invisible

string indicating if some points should not be drawn ("ind", "ind.sup" or "quali" for the individual graph and "var" or "quanti.sup" for the correlation circle graph)

lim.cos2.var

value of the square cosinus under the variables are not drawn

title

string corresponding to the title of the graph you draw (by default NULL and a title is chosen)

palette

the color palette used to draw the points. By default colors are chosen. If you want to define the colors : palette=palette(c("black","red","blue")); or you can use: palette=palette(rainbow(30)), or in black and white for example: palette=palette(gray(seq(0,.9,len=25)))

autoLab

if autoLab="auto", autoLab is equal to "yes" if there are less than 50 elements and "no" otherwise; if "yes", the labels of the drawn elements are placed in a "good" way (can be time-consuming if many elements), and if "no" the elements are placed quickly but may overlap

new.plot

boolean, if TRUE, a new graphical device is created

select

a selection of the elements that are drawn; see the details section

unselect

may be either a value between 0 and 1 that gives the transparency of the unselected objects (if unselect=1 the transparceny is total and the elements are not drawn, if unselect=0 the elements are drawn as usual but without any label) or may be a color (for example unselect="grey60")

shadowtext

boolean; if true put a shadow on the labels (rectangles are written under the labels which may lead to difficulties to modify the graph with another program)

legend

a list of arguments that defines the legend if needed (when individuals are drawn according to a variable); see the arguments of the function legend

...

further arguments passed to or from other methods, such as cex, cex.main, ...

Value

Returns the individuals factor map and the variables factor map.

Details

The argument autoLab = "yes" is time-consuming if there are many labels that overlap. In this case, you can modify the size of the characters in order to have less overlapping, using for example cex=0.7. The select argument can be used in order to select a part of the elements (individuals if you draw the graph of individuals, or variables if you draw the graph of variables) that are drawn. For example, you can use: select = 1:5 and then the elements 1:5 are drawn. select = c("name1","name5") and then the elements that have the names name1 and name5 are drawn. select = "coord 10" and then the 10 elements that have the highest (squared) coordinates on the 2 chosen dimensions are drawn. select = "contrib 10" and then the 10 elements that have the highest contribution on the 2 dimensions of your plot are drawn. select = "cos2 5" and then the 5 elements that have the highest cos2 on the 2 dimensions of your plot are drawn. select = "dist 8" and then the 8 elements that have the highest distance to the center of gravity are drawn.

Examples

Run this code

data(decathlon)
res.pca <- PCA(decathlon, quanti.sup = 11:12, quali.sup = 13)
plot(res.pca, habillage = 13, col.hab=c("green","blue"))
## To automatically draw ellipses around the barycentres of all the categorical variables
plotellipses(res.pca)
## Selection of some individuals
plot(res.pca,select="contrib 7") #plot the 7 individuals that have the highest cos2 
plot(res.pca,select="cos2 0.8")  #plot the individuals that have a cos2 greater than 0.8
plot(res.pca,select="cos2 5")     #plot the 5 individuals that have the highest cos2 
plot(res.pca,choix="var",select="cos2 0.6")  #plot the variables that have a cos2 greater than 0.6