Drawing lines
With vectorization we can draw multiple points at the same time by providing the coordinates to the points as vectors.
# empty plot
plot(NULL, xlim=c(-1, 1), ylim=c(-1,1))
# the coordinates
xVect2 <- seq(-1, 1, 0.2)
yVect2 <- c(0.4, 0.9, 0, -0.6, -0.5, 0.1, 0.3, -0.7, 0.5, -0.9, 0.6)
points(x=xVect2, y=yVect2, pch=16)
Besides saving the time and effort by not having to use iteration explicitly, this kind of syntax allows us to define how the points should be connected. This is exactly what the lines() function does. Its syntax is almost exactly the same as that of points():
# empty plot
plot(NULL, xlim=c(-1, 1), ylim=c(-1,1))
# the coordinates
lines(x=xVect2, y=yVect2)
You have the option to modify the type of the line plot. This describes the relationship between the point coordinates and the actual lines. See ?lines and search for type argument, which will direct to possible argumets for the type.
Similar to segments(), abline() and rect() you can set the lty argument for the line style (solid, dashed, dotted), and the lwd argument for the with of the line.
# empty plot
plot(NULL, xlim=c(-1, 1), ylim=c(-1,1))
# the coordinates
lines(x=xVect2, y=yVect2, type="o", lty=3, col="blue")
Similar to
points()thelines()function is extremely important in practical data analysis. It is frequently used to visualize series of points such as time series.