title: Poisson confidence interval with numpy
body: <p>I'm trying to put Poisson continuous error bars on a histogram I'm making with matplotlib, but I can't seem to find a numpy function that will given me a 95% confidence interval assuming poissonian data. Ideally the solution doesn't depend on scipy, but anything will work. Does such a function exist? I've found a lot about bootstrapping but this seems a bit excessive in my case. </p>