Polar contour plot in Matplotlib

I have a set of data that I want to use to produce a contour plot in polar co-ordinates using Matplotlib.

My data is the following:

• theta - 1D array of angle values
• radius - 1D array of radius values
• value - 1D array of values that I want to use for the contours

These are all 1D arrays that align properly - eg:

theta   radius   value
30      1        2.9
30      2        5.3
35      5        9.2

That is, all of the values are repeated enough times so that each row of this 'table' of three variables defines one point.

How can I create a polar contour plot from these values? I've thought about converting the radius and theta values to x and y values and doing it in cartesian co-ordinates, but the contour function seems to require 2D arrays, and I can't quite understand why.

Any ideas?