Other

display(val)

Prints a representation of the value val to the console.

expectation(dist[, fn])

Computes the expectation of a function fn under the distribution given by dist. The distribution dist must have finite support.

fn defaults to the identity function when omitted.

expectation(Categorical({ps: [.2, .8], vs: [0, 1]})); // => 0.8
marginalize(dist, project)

Marginalizes out certain variables in a distribution. project can be either a function or a string. Using it as a function:

var dist = Infer({model: function() {
  var a = flip(0.9);
  var b = flip();
  var c = flip();
  return {a: a, b: b, c: c};
}});

marginalize(dist, function(x) {
  return x.a;
}) // => Marginal with p(true) = 0.9, p(false) = 0.1

Using it as a string:

marginalize(dist, 'a') // => Marginal with p(true) = 0.9, p(false) = 0.1
forward(model)

Evaluates function of zero arguments model, ignoring any factor statements.

Also see: Forward Sampling

forwardGuide(model)

Evaluates function of zero arguments model, ignoring any factor statements, and sampling from the guide at each random choice.

Also see: Forward Sampling

mapObject(fn, obj)

Returns the object obtained by mapping the function fn over the values of the object obj. Each application of fn has a property name as its first argument and the corresponding value as its second argument.

var pair = function(x, y) { return [x, y]; };
mapObject(pair, {a: 1, b: 2}); // => {a: ['a', 1], b: ['b', 2]}
extend(obj1, obj2, ...)

Creates a new object and assigns own enumerable string-keyed properties of source objects 1, 2, ... to it. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources.

var x = { a: 1, b: 2 };
var y = { b: 3, c: 4 };
extend(x, y);  // => { a: 1, b: 3, c: 4 }
cache(fn, maxSize)

Returns a memoized version of fn. The memoized function is backed by a cache that is shared across all executions/possible worlds.

cache is provided as a means of avoiding the repeated computation of a deterministic function. The use of cache with a stochastic function is unlikely to be appropriate. For stochastic memoization see mem().

When maxSize is specified the memoized function is backed by a LRU cache of size maxSize. The cache has unbounded size when maxSize is omitted.

cache can be used to memoize mutually recursive functions, though for technical reasons it must currently be called as dp.cache for this to work.

mem(fn)

Returns a memoized version of fn. The memoized function is backed by a cache that is local to the current execution.

Internally, the memoized function compares its arguments by first serializing them with JSON.stringify. This means that memoizing a higher-order function will not work as expected, as all functions serialize to the same string.

error(msg)

Halts execution of the program and prints msg to the console.