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| // Written for webppl dev branch -- there may be breaking changes | |
| var init = function(n,y){ | |
| return repeat(n, function(){ return y; }); | |
| }; | |
| var step = function(states, p, n){ | |
| return map( | |
| function(x) { return x + binomial(p,n) }, | |
| states | |
| ); | |
| }; | |
| var count_complete = function(finish){ | |
| return filter(function(x){ | |
| return x > -1; | |
| }, finish).length; | |
| }; | |
| var update_finish_times = function(finish, state, t, end){ | |
| return map2( | |
| function(s,f) { | |
| if(f != -1) { return f; } | |
| if(s >= end) { | |
| return t; | |
| } else { | |
| return f; | |
| } | |
| }, | |
| state, | |
| finish | |
| ); | |
| }; | |
| var accumulators = function(n, modelParams, finish, state, t){ | |
| var finished_count = count_complete(finish); | |
| var p_this = 1 - Math.pow(1 - modelParams.p, | |
| 1 + modelParams.boost*finished_count); | |
| var newState = step(state, p_this, modelParams.end); | |
| var newFinish = update_finish_times(finish, newState, t, modelParams.end); | |
| if(count_complete(newFinish) == n){ | |
| return sort(newFinish); | |
| } else { | |
| return accumulators(n, modelParams, newFinish, newState, t+1); | |
| } | |
| }; | |
| // Example data (not sure what form yours are in) | |
| var data = [4]; | |
| var n = data.length; | |
| var model = function(){ | |
| var modelParams = { | |
| p : beta({a: 2, b: 20}), | |
| end : discrete({ps: init(100,0.01)}), | |
| boost : gamma({shape: 1.64, scale: 0.64}) // mode ~ 1, sd ~ 2 | |
| }; | |
| var initState = init(n, 0); | |
| var initFinish = init(n, -1); | |
| var modelOutput = Infer({method: 'rejection', samples: 1000}, function() { | |
| return accumulators(n, modelParams, initFinish, initState, 1); | |
| }); | |
| factor(modelOutput.score(data)); | |
| return modelParams; | |
| }; | |
| Infer({method: 'MCMC', samples: 100, verbose : true}, | |
| model); |
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