points {graphics}  R Documentation 
points
is a generic function to draw a sequence of points at
the specified coordinates. The specified character(s) are plotted,
centered at the coordinates.
points(x, ...) ## Default S3 method: points(x, y = NULL, type = "p", pch = par("pch"), col = par("col"), bg = NA, cex = 1, ...)
x, y 
coordinate vectors of points to plot. 
type 
character indicating the type of plotting; actually any of
the type s as in plot . 
pch 
plotting “character”, i.e., symbol to use. pch can
either be a single character or an integer code for one of a set of
graphics symbols. The full set of S symbols is available with
pch=0:18 , see the last picture from example(points) ,
i.e., the examples below.
In addition, there is a special set of R plotting symbols which can be obtained with pch=19:25 and 21:25 can be
colored and filled with different colors:
pch=26:32 are currently unused, and pch=32:255
give the text symbol in a singlebyte locale. In a multibyte locale
such as UTF8, numeric values of pch greater than or equal to
32 specify a Unicode code point (except for the symbol font as
selected by par(font = 5) ).
If pch is an integer or character NA or an empty
character string, the point is omitted from the plot.
Value pch="." is handled specially. It is a rectangle of
side 0.01 inch (scaled by cex ). In addition, if cex =
1 (the default), each side is at least one pixel (1/72 inch on
the pdf , postscript and
xfig devices). The details here have been changed
for 2.1.0 and are subject to change.

col 
color code or name, see par . 
bg 
background (“fill”) color for open plot symbols given by
pch=21:25 . 
cex 
character (or symbol) expansion: a numerical vector.
This works as a multiple of par("cex") . 
... 
Further graphical parameters (see plot.xy
and par ) may also be supplied as arguments. 
The coordinates can be passed in a plotting structure
(a list with x
and y
components), a twocolumn matrix, a
time series, .... See xy.coords
.
Arguments pch
, col
, bg
, cex
and lwd
can be vectors (which will be recycled as needed) giving a value for each
point plotted. If lines are to be plotted (e.g. for
type = "b"
the first element of lwd
is used.
Points whose x
, y
, pch
, col
or cex
value is NA
are omitted from the plot.
Graphical parameters are permitted as arguments to this function.
What is meant by ‘a single character’ is localedependent.
The encoding may not have symbols for some or all of the characters in
pch=128:255
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
plot
, lines
, and the underlying
“primitive” plot.xy
.
plot(4:4, 4:4, type = "n")# setting up coord. system points(rnorm(200), rnorm(200), col = "red") points(rnorm(100)/2, rnorm(100)/2, col = "blue", cex = 1.5) op < par(bg = "light blue") x < seq(0,2*pi, len=51) ## something "between type='b' and type='o'": plot(x, sin(x), type="o", pch=21, bg=par("bg"), col = "blue", cex=.6, main='plot(..., type="o", pch=21, bg=par("bg"))') par(op) ## Showing all the extra & some char graphics symbols  Pex < 3 ## good for both .Device=="postscript" and "x11" ipch < 0:35; np < length(ipch); k < floor(sqrt(np)); dd < c(1,1)/2 rx < dd + range(ix < ipch %/% k) ry < dd + range(iy < 3 + (k1) ipch %% k) pch < as.list(ipch) pch[26+ 1:10] < as.list(c("*",".", "o","O","0","+","","","%","#")) plot(rx, ry, type="n", axes = FALSE, xlab = "", ylab = "", main = paste("plot symbols : points (... pch = *, cex =", Pex,")")) abline(v = ix, h = iy, col = "lightgray", lty = "dotted") for(i in 1:np) { pc < pch[[i]] points(ix[i], iy[i], pch = pc, col = "red", bg = "yellow", cex = Pex) ## red symbols with a yellow interior (where available) text(ix[i]  .3, iy[i], pc, col = "brown", cex = 1.2) }