add data points to existing plot in R

Question

I try to receive the data from a sensor from time to time and plot it in real time. That means the length of the dataset is not know before hand. And need to adjust the range of the graph dynamically.

I tried the following

plot(1,10, xlim=range(0,10), ylim=range(0,10), type='n')

points(1,data[1]) 

points(2,data[2])

But once the number of dots is beyond the range of x axis (10 in this case), the data points are out of the range. How to adjust the range accordingly?

Answer 1

Just issue a new plot command with an expanded range. On modern computers the time taken to recreate the plot is small and you generally will not see a delay. Any other approach will essentially do the same thing, clear the current plot and create a new plot.

The ggplot2 and lattice packages have ways of constructing a plot and updating the plot, but when the updated plot is shown it is redrawn from scratch.

There is a zoomplot function in the TeachingDemos package which will allow you to change the range of a plot, but it also will just redraw the plot from scratch (and due to changes in R 3.0.0 it is not currently working, so if you wanted to use it you would need to go back to R 2.15 or before, or wait for it to be fixed).

Answer 2

You can't adjust the range dynamically (sometimes Excel is better). However, you can keep track of what you've plotted, and redo the plot when you've reached the limit. You could also just make a new plot every time you get more data, which would be a way of faking a dynamic update.