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141 lines
4.3 KiB
Python
Executable File
141 lines
4.3 KiB
Python
Executable File
#!/usr/bin/env python
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'''
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Digit recognition adjustment.
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Grid search is used to find the best parameters for SVM and KNearest classifiers.
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SVM adjustment follows the guidelines given in
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http://www.csie.ntu.edu.tw/~cjlin/papers/guide/guide.pdf
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Usage:
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digits_adjust.py [--model {svm|knearest}]
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--model {svm|knearest} - select the classifier (SVM is the default)
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'''
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# Python 2/3 compatibility
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from __future__ import print_function
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import sys
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PY3 = sys.version_info[0] == 3
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if PY3:
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xrange = range
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import numpy as np
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import cv2 as cv
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from multiprocessing.pool import ThreadPool
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from digits import *
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def cross_validate(model_class, params, samples, labels, kfold = 3, pool = None):
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n = len(samples)
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folds = np.array_split(np.arange(n), kfold)
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def f(i):
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model = model_class(**params)
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test_idx = folds[i]
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train_idx = list(folds)
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train_idx.pop(i)
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train_idx = np.hstack(train_idx)
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train_samples, train_labels = samples[train_idx], labels[train_idx]
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test_samples, test_labels = samples[test_idx], labels[test_idx]
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model.train(train_samples, train_labels)
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resp = model.predict(test_samples)
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score = (resp != test_labels).mean()
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print(".", end='')
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return score
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if pool is None:
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scores = list(map(f, xrange(kfold)))
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else:
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scores = pool.map(f, xrange(kfold))
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return np.mean(scores)
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class App(object):
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def __init__(self):
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self._samples, self._labels = self.preprocess()
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def preprocess(self):
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digits, labels = load_digits(DIGITS_FN)
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shuffle = np.random.permutation(len(digits))
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digits, labels = digits[shuffle], labels[shuffle]
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digits2 = list(map(deskew, digits))
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samples = preprocess_hog(digits2)
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return samples, labels
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def get_dataset(self):
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return self._samples, self._labels
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def run_jobs(self, f, jobs):
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pool = ThreadPool(processes=cv.getNumberOfCPUs())
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ires = pool.imap_unordered(f, jobs)
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return ires
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def adjust_SVM(self):
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Cs = np.logspace(0, 10, 15, base=2)
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gammas = np.logspace(-7, 4, 15, base=2)
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scores = np.zeros((len(Cs), len(gammas)))
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scores[:] = np.nan
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print('adjusting SVM (may take a long time) ...')
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def f(job):
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i, j = job
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samples, labels = self.get_dataset()
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params = dict(C = Cs[i], gamma=gammas[j])
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score = cross_validate(SVM, params, samples, labels)
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return i, j, score
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ires = self.run_jobs(f, np.ndindex(*scores.shape))
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for count, (i, j, score) in enumerate(ires):
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scores[i, j] = score
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print('%d / %d (best error: %.2f %%, last: %.2f %%)' %
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(count+1, scores.size, np.nanmin(scores)*100, score*100))
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print(scores)
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print('writing score table to "svm_scores.npz"')
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np.savez('svm_scores.npz', scores=scores, Cs=Cs, gammas=gammas)
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i, j = np.unravel_index(scores.argmin(), scores.shape)
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best_params = dict(C = Cs[i], gamma=gammas[j])
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print('best params:', best_params)
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print('best error: %.2f %%' % (scores.min()*100))
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return best_params
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def adjust_KNearest(self):
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print('adjusting KNearest ...')
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def f(k):
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samples, labels = self.get_dataset()
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err = cross_validate(KNearest, dict(k=k), samples, labels)
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return k, err
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best_err, best_k = np.inf, -1
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for k, err in self.run_jobs(f, xrange(1, 9)):
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if err < best_err:
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best_err, best_k = err, k
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print('k = %d, error: %.2f %%' % (k, err*100))
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best_params = dict(k=best_k)
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print('best params:', best_params, 'err: %.2f' % (best_err*100))
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return best_params
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if __name__ == '__main__':
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import getopt
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import sys
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print(__doc__)
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args, _ = getopt.getopt(sys.argv[1:], '', ['model='])
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args = dict(args)
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args.setdefault('--model', 'svm')
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args.setdefault('--env', '')
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if args['--model'] not in ['svm', 'knearest']:
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print('unknown model "%s"' % args['--model'])
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sys.exit(1)
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t = clock()
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app = App()
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if args['--model'] == 'knearest':
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app.adjust_KNearest()
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else:
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app.adjust_SVM()
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print('work time: %f s' % (clock() - t))
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