Using np.piecewise for a uniform distribution

Question

I want to plot the following cumulative distribution function

and to do this I thought I could use np.piecewise as follows

x = np.linspace(3, 9, 100)
np.piecewise(x, [x < 3, 3 <= x <= 9, x > 9], [0, float((x - 3)) / (9 - 3), 1])

but this gives the following error

ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

How can I do this?

Answer 1

np.piecewise is a capricious beast.

Use :

x = np.linspace(3, 9, 100)
cond = [x < 3, (3 <= x) & (x <= 9), x > 9];
func = [0, lambda x : (x - 3) / (9 - 3), 1];
np.piecewise(x, cond, func)

Explanations here.