How to plot 1-d data at given y-value with pylab

Question

I want to plot the data points that are in a 1-D array just along the horizontal axis [edit: at a given y-value], like in this plot:

Answer 1

This will plot the array "ar":

import matplotlib.pyplot as pp
ar = [1, 2, 3, 8, 4, 5]
pp.plot(ar)
pp.show()

If you are using ipython, you can start it with the "-pylab" option and it will import numpy and matplotlib automatically on startup, so you just need to write:

ar = [1, 2, 3, 8, 4, 5]
plot(ar)

To do a scatter plot with the y coordinate set to 1:

plot(ar, len(ar) * [1], "x")