This post is just an excuse for me to put up what I thought is a cool graphic. It's the progress of a set of 10 independent random walks, with equal probability of going up or down at each step, and the progress is plotted using R. This is probably

*not the right way to do it*in R. I often have trouble when I want to do something that seems like it should use individual values rather than vectors. Anyway, here goes.

• in the first part, we just set the random number generator, the number of steps N, and set up a plot with type = 'n' so that it makes an empty plot of the right size but doesn't actually plot anything yet.

• next, we get the colors for each of the 10 individual walks and set up a source for the steps. One should be able to just do sample(c(-1,1), replace=T), but I wasn't happy with the distributions I got. I don't know if it's really a difference.

• in the main part we have an outer loop that goes through the walks, and an inner loop that does the steps. The line where I do y = sum(y,d) is the weird part. y = y + d didn't work. Then we just plot points and lines in the usual way. If you're unsure about the arguments just do ?points or ?lines.