R TUTORIAL, Part I: Plotting

R is a statistical analyzation language, and that means it is very good at data manipulation and data analyzation. One key way to analyze data is through plotting, and R excels in this field. R provides a variety of plotting capabilities. The basic command is plot: In this chapter, we discuss some techniques for manipulating with graphs that will be useful for presenting solutions to the initial value problems:

\[ y' = f(x,y), \qquad y(x_0 ) = y_0 . \]

Plotting

Our first example starts with discrete plot. R will take two vectors, x and y, of the same length, and will plot them against each other. For example,

When a function is defined by an analytic formula involving functions that R knows, we can make a simple graph. This is using R's built-in plot function to plot a 2d function. In R, you cannot plot a function without first creating points and applying the function to the points. The plot function will plot these points as a scatterplot. To plot a continuous line, specify type = "l"

and with different step size:

We can change the width of the curve and add a text as the following example shows

Instead of line, we can use circles:

It is possible to plot multiple functions on the same graph, plot the first function and call "lines" for every additional function, which adds each function to the original plot.

 

  1. Schiesser, W.E., An Introductory Comparison of Matlab and R, Lehigh University, Bethlehem, USA.
  2. Soetaert, K, Cash, J., Mazzia, F., Solving Differential Equations in R, 2012, Springer, Heidelberg New York Dordrecht London