# pch in R

This tutorial demonstrates the use of `pch` in R.

## `pch` in R

The `pch` abbreviated as `plot character` is the standard argument used to set the character, which will be plotted in different R functions. The `pch` also can be defined as the explanatory symbol added to a plot; this explanatory text includes legends, axis labels, or titles.

The `pch` are the symbols you want to add to a plot that explains a certain thing. Here is the list of `pch` symbols with their values.

``````pch = 0 square
pch = 1 circle
pch = 2 point up triangle
pch = 3 plus
pch = 4 cross
pch = 5 diamond
pch = 6 point-down triangle
pch = 7 square cross
pch = 8 star
pch = 9 diamond plus
pch = 10 circle plus
pch = 11 up and down triangles
pch = 12 square plus
pch = 13 circle cross
pch = 14 square and down triangle
pch = 15 filled square
pch = 16 filled circle
pch = 17 point-up filled triangle
pch = 18 filled diamond
pch = 19 solid circle
pch = 20 bullet (smaller circle)
pch = 21 filled circle blue
pch = 22 filled square blue
pch = 23 filled diamond blue
pch = 24 filled triangle point-up blue
pch = 25 filled triangle point down blue
``````

The `pch` is passed as an argument to the legend; the `pch` method will include the value from the above list. Let’s try an example for the `pch`.

``````#data
set.seed(1234)
delftstack <- data.frame(x=runif(10),y=runif(10),
color=rep(c("lightblue","red"),5),
background=rep(c("red", "lightblue"),5),
shape=rep(c(21,24),5),stringsAsFactors = FALSE)

#plot
plot(delftstack\$x,delftstack\$y,col=delftstack\$color,bg=delftstack\$background,pch=delftstack\$shape,cex=2)
points(x=0.5,y=0.5,pch=8,col="red",cex=2)

#add a legend, pt.bg is needed to fill in the background of the shape
legend(0.01,0.5,
legend = c(expression("PCH"["Example1"]),
expression("PCH"["Example2"]),
expression("PCH"["Example"])),
pch = c(21,24,8),
col = c("lightblue","red","red"),
pt.bg = c("red","lightblue"),
cex=2)
``````

The code above plots the data from the data frame, and then in legend, it tries to apply some characteristics, which also includes `pch`. See the output: 