Defining P and Q

Here, we document all the alan functionality you need to define the structure of the prior, P, and approximate posterior, Q.

A relatively complete example of all the features is given below:

from alan import Plate, Normal, Group, Data, QEMParam, OptParam

P_plate = Plate(
    a = Normal(0., 1),
    bc = Group(
        b = Normal('a', 1),
        c = Normal('b', lambda a: a.exp()),
    ),
    p1 = Plate(
        d = Normal("c", 1),
        e = Normal("d", 1.),
    ),
)

Q_plate = Plate(
    a = Normal(QEMParam(0.), QEMParam(1.)),
    bc = Group(
        b = Normal(QEMParam(0.), QEMParam(1.)),
        c = Normal(0., 1.),
    ),
    p1 = Plate(
        d = Normal(OptParam(0.), OptParam(1.)),
        e = Data(),
    ),
)

This example showcases several features:

Contents: