Mercurial > pylearn
annotate stopper.py @ 507:b8e6de17eaa6
modifs to smallNorb
| author | James Bergstra <bergstrj@iro.umontreal.ca> |
|---|---|
| date | Wed, 29 Oct 2008 18:06:49 -0400 |
| parents | 0ea793361d85 |
| children |
| rev | line source |
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| 178 | 1 """Early stopping iterators |
| 2 | |
| 3 The idea here is to supply early-stopping heuristics that can be used in the | |
| 4 form: | |
| 5 | |
| 6 stopper = SomeEarlyStopper() | |
| 7 | |
| 8 for i in stopper(): | |
| 9 # train from data | |
| 10 if i.set_score: | |
| 11 i.score = validation_score | |
| 12 | |
| 13 | |
| 14 So far I only have one heuristic, so maybe this won't scale. | |
| 15 """ | |
| 16 | |
| 17 class Stopper(object): | |
| 18 | |
| 19 def train(self, data, update_rows_fn, update, validate, save=None): | |
| 20 """Return the best model trained on data | |
| 21 | |
| 22 Parameters: | |
| 23 data - a thing that accepts getitem(<list of int64>), or a tuple of such things | |
| 24 update_rows_fn - fn : int --> <list or tensor of int> | |
| 25 update - fn: update an internal model from elements of data | |
| 26 validate - fn: evaluate an internal model based on elements of data | |
| 27 save - fn: return a copy of the internal model | |
| 28 | |
| 29 The body of this function exhausts the <self> iterator, and trains a | |
| 30 model using early stopping in the process. | |
| 31 """ | |
| 32 | |
| 33 best = None | |
| 34 for stp in self: | |
| 35 i = stp.iter | |
| 36 | |
| 37 # call update on some training set rows | |
| 38 t_rows = update_rows_fn(i) | |
| 39 if isinstance(data, (tuple, list)): | |
| 40 update(*[d[t_rows] for d in data]) | |
| 41 else: | |
| 42 update(data[t_rows]) | |
| 43 | |
| 44 if stp.set_score: | |
| 45 stp.score = validate() | |
| 46 if (stp.score < stp.best_score) and save: | |
| 47 best = save() | |
| 48 return best | |
| 49 | |
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50 def find_min(self, step, check, save): |
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51 best = None |
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52 for stp in self: |
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53 step() |
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54 if stp.set_score: |
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55 stp.score = check() |
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56 if (stp.score < stp.best_score) and save: |
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57 best = (save(), stp.iter, stp.score) |
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58 return best |
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59 |
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60 |
| 178 | 61 |
| 62 class ICML08Stopper(Stopper): | |
| 63 @staticmethod | |
| 64 def icml08(ntrain, batchsize): | |
| 65 """Some setting similar to what I used for ICML08 submission""" | |
| 66 #TODO: what did I actually use? put that in here. | |
| 67 return ICML08Stopper(30*ntrain/batchsize, | |
| 68 ntrain/batchsize, 0.96, 2.0, 100000000) | |
| 69 | |
| 70 def __init__(self, i_wait, v_int, min_improvement, patience, hard_limit): | |
| 71 self.initial_wait = i_wait | |
| 72 self.set_score_interval = v_int | |
| 73 self.min_improvement = min_improvement | |
| 74 self.patience = patience | |
| 75 self.hard_limit = hard_limit | |
| 76 | |
| 77 self.best_score = float('inf') | |
| 78 self.best_iter = -1 | |
| 79 self.iter = -1 | |
| 80 | |
| 81 self.set_score = False | |
| 82 self.score = None | |
| 83 | |
| 84 def __iter__(self): | |
| 85 return self | |
| 86 | |
| 87 E_set_score = 'when iter.set_score is True, caller must assign a score to iter.score' | |
| 88 def next(self): | |
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in __get__, problem if the i.stop was None, i being the slice, added one line replacing None by the len(self)
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89 |
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cc96f93a7810
previous commit was supposed to concern only one file, dataset.py, try to undo my other changes with this commit (nothing was broken though, just useless debugging prints)
Thierry Bertin-Mahieux <bertinmt@iro.umontreal.ca>
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90 #print 'ICML08 stopper, were doing a next' |
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in __get__, problem if the i.stop was None, i being the slice, added one line replacing None by the len(self)
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91 |
| 178 | 92 if self.set_score: #left over from last time |
| 93 if self.score is None: | |
| 94 raise Exception(ICML08Stopper.E_set_score) | |
| 95 if self.score < (self.best_score * self.min_improvement): | |
| 96 (self.best_score, self.best_iter) = (self.score, self.iter) | |
| 97 self.score = None #un-set it | |
| 98 | |
| 99 | |
| 100 starting = self.iter < self.initial_wait | |
| 101 waiting = self.iter < (self.patience * self.best_iter) | |
| 102 if starting or waiting: | |
| 103 # continue to iterate | |
| 104 self.iter += 1 | |
| 105 if self.iter == self.hard_limit: | |
| 106 raise StopIteration | |
| 107 self.set_score = (self.iter % self.set_score_interval == 0) | |
| 108 return self | |
| 109 | |
| 110 raise StopIteration | |
| 111 | |
| 112 | |
| 113 class NStages(ICML08Stopper): | |
| 114 """Run for a fixed number of steps, checking validation set every so | |
| 115 often.""" | |
| 116 def __init__(self, hard_limit, v_int): | |
| 117 ICML08Stopper.__init__(self, hard_limit, v_int, 1.0, 1.0, hard_limit) | |
| 118 | |
| 119 #TODO: could optimize next() function. Most of what's in ICML08Stopper.next() | |
| 120 #is not necessary | |
| 121 | |
| 122 |