Learn R Programming

labdsv (version 1.3-1)

plot.pca: Plotting Routines For Principal Components Ordinations

Description

A set of routines for plotting, highlighting points, or adding fitted surfaces to PCAs.

Usage

## S3 method for class 'pca':
plot(x, ax = 1, ay = 2, col = 1, title = "", pch = 1, \dots)
## S3 method for class 'pca':
points(x, which, ax = 1, ay = 2, col = 2, pch = 1, cex = 1, \dots)
## S3 method for class 'pca':
plotid(ord, ids = seq(1:nrow(ord$scores)), ax = 1, ay = 2,
    col = 1, ...)
## S3 method for class 'pca':
hilight(ord, overlay, ax = 1, ay = 2, cols=c(2,3,4,5,6,7), glyph=c(1,3,5),
    origpch = 1, blank = '#FFFFFF', ...)
## S3 method for class 'pca':
chullord(ord, overlay, ax = 1, ay = 2, cols=c(2,3,4,5,6,7), ltys = c(1,2,3), ...)
## S3 method for class 'pca':
surf(ord, var, ax = 1, ay = 2, col = 2, labcex = 0.8,
    family = gaussian, thinplate=TRUE, grid=50, gamma=1, \dots)
## S3 method for class 'pca':
varplot(x, dim=length(x$sdev))

Arguments

x
an object of class pca
ax
the dimension to use for the X axis
ay
the dimension to use for the Y axis
title
a title for the plot
which
a logical variable to specify points to be highlighted
ord
an object of class pca
overlay
a factor or integer vector to hilight or distinguish
cols
the sequence of color indices to be used
glyph
the sequence of glyphs (pch) to be used
origpch
the pch number of the glyph employed in the original plot (to be obliterated by blank)
blank
the color to use to erase the glyphs of the original plot
ltys
the sequence of line types to be used
var
a variable to be surfaced
family
controls the link function passed to gam: one of gaussian, binomial, or poisson
ids
identifier labels for samples. Defaults to 1:n
dim
number of dimensions to include in barplot
col
color index for points or contours
labcex
size of contour interval labels
thinplate
a logical swith to control using thinplate splines versus independent additive fits
gamma
controls the smoothness of the fit from gam
grid
the number of X and Y values used in establishing a grid
pch
plot character: glyph to plot
cex
character expansion factor: size of plotted characters
...
arguments to pass to the plot function

Value

  • Function plotid returns a vector of row numbers of identified plots.

    Function varplot.pca produces two plots: (1) the variance accounted for by eigenvector up to the specified number of dimensions (default = all), and (2) the cumulative variance accounted for by dimension.

Details

Function plot produces a scatterplot of sample scores for the specified axes, erasing or over-plotting on the current graphic device. Axes dimensions are controlled to produce a graph with the correct aspect ratio. Functions points, plotid, hilight, chullord, and surf add detail to an existing plot. The axes specified must match the underlying plot exactly.

Function plotid identifies and labels samples (optionally with values from a third vector) in the PCA, and requires interaction with the mouse: left button identifies, right button exits.

Function points is passed a logical vector to identify a set of samples by color of glyph. It can be used to identify a single set meeting almost any criterion that can be stated as a logical expression.

Function hilight is passed a factor vector or integer vector, and identifies factor values by color and glyph. By specifying values for arguments cols and glyph it is possible to control the sequence of colors and pch glyphs used in the hilight.

Function chullord is passed a factor vector or integer vector, and plots a convex hull around all points in each factor class. By specifying values for arguments cols and ltys it is possible to control the sequence of colors and linetypes of the convex hulls.

Function surf calculates and plots fitted surfaces for logical or quantitative variables. The function employs the gam function to fit a variable to the ordination coordinates, and to predict the values at all grid points. The grid is established with the expand.grid function, and the grid is then specified in a call to gam.predict. The predicted values are trimmed to the the convex hull of the data, and the contours are fit by contour. The default link function for fitting the GAMs is gaussian, suitable for unbounded continuous variables. For logical variables you should specify family = binomial to get a logistic GAM, and for integer counts you should specify family = poisson to get a Poisson GAM.

References

http://ecology.msu.montana.edu/labdsv/R/labdsv

Examples

Run this code
data(bryceveg)
data(brycesite)
pca.1 <- pca(bryceveg)
plot(pca.1)
points(pca.1,brycesite$elev>8000)
surf(pca.1,brycesite$elev)
plotid(pca.1,ids=row.names(bryceveg))

Run the code above in your browser using DataLab