Python RealFeatures.set_feature_matrix方法代码示例

# 需要导入模块: from modshogun import RealFeatures [as 别名]
# 或者: from modshogun.RealFeatures import set_feature_matrix [as 别名]
def modelselection_grid_search_kernel (num_subsets, num_vectors, dim_vectors):
	# init seed for reproducability
	Math.init_random(1)
	random.seed(1);

	# create some (non-sense) data
	matrix=random.rand(dim_vectors, num_vectors)

	# create num_feautres 2-dimensional vectors
	features=RealFeatures()
	features.set_feature_matrix(matrix)

	# create labels, two classes
	labels=BinaryLabels(num_vectors)
	for i in range(num_vectors):
		labels.set_label(i, 1 if i%2==0 else -1)

	# create svm
	classifier=LibSVM()

	# splitting strategy
	splitting_strategy=StratifiedCrossValidationSplitting(labels, num_subsets)

	# accuracy evaluation
	evaluation_criterion=ContingencyTableEvaluation(ACCURACY)

	# cross validation class for evaluation in model selection
	cross=CrossValidation(classifier, features, labels, splitting_strategy, evaluation_criterion)
	cross.set_num_runs(1)

	# print all parameter available for modelselection
	# Dont worry if yours is not included, simply write to the mailing list
	#classifier.print_modsel_params()

	# model parameter selection
	param_tree=create_param_tree()
	#param_tree.print_tree()

	grid_search=GridSearchModelSelection(cross, param_tree)

	print_state=False
	best_combination=grid_search.select_model(print_state)
	#print("best parameter(s):")
	#best_combination.print_tree()

	best_combination.apply_to_machine(classifier)

	# larger number of runs to have tighter confidence intervals
	cross.set_num_runs(10)
	cross.set_conf_int_alpha(0.01)
	result=cross.evaluate()
	casted=CrossValidationResult.obtain_from_generic(result);
	#print "result mean:", casted.mean

	return classifier,result,casted.mean

# 需要导入模块: from modshogun import RealFeatures [as 别名]
# 或者: from modshogun.RealFeatures import set_feature_matrix [as 别名]
def hsic_graphical():
	# parameters, change to get different results
	m=250
	difference=3

	# setting the angle lower makes a harder test
	angle=pi/30

	# number of samples taken from null and alternative distribution
	num_null_samples=500

	# use data generator class to produce example data
	data=DataGenerator.generate_sym_mix_gauss(m,difference,angle)

	# create shogun feature representation
	features_x=RealFeatures(array([data[0]]))
	features_y=RealFeatures(array([data[1]]))

	# compute median data distance in order to use for Gaussian kernel width
	# 0.5*median_distance normally (factor two in Gaussian kernel)
	# However, shoguns kernel width is different to usual parametrization
	# Therefore 0.5*2*median_distance^2
	# Use a subset of data for that, only 200 elements. Median is stable
	subset=int32(array([x for x in range(features_x.get_num_vectors())])) # numpy
	subset=random.permutation(subset) # numpy permutation
	subset=subset[0:200]
	features_x.add_subset(subset)
	dist=EuclideanDistance(features_x, features_x)
	distances=dist.get_distance_matrix()
	features_x.remove_subset()
	median_distance=np.median(distances)
	sigma_x=median_distance**2
	features_y.add_subset(subset)
	dist=EuclideanDistance(features_y, features_y)
	distances=dist.get_distance_matrix()
	features_y.remove_subset()
	median_distance=np.median(distances)
	sigma_y=median_distance**2
	print "median distance for Gaussian kernel on x:", sigma_x
	print "median distance for Gaussian kernel on y:", sigma_y
	kernel_x=GaussianKernel(10,sigma_x)
	kernel_y=GaussianKernel(10,sigma_y)

	# create hsic instance. Note that this is a convienience constructor which copies
	# feature data. features_x and features_y are not these used in hsic.
	# This is only for user-friendlyness. Usually, its ok to do this.
	# Below, the alternative distribution is sampled, which means
	# that new feature objects have to be created in each iteration (slow)
	# However, normally, the alternative distribution is not sampled
	hsic=HSIC(kernel_x,kernel_y,features_x,features_y)

	# sample alternative distribution
	alt_samples=zeros(num_null_samples)
	for i in range(len(alt_samples)):
		data=DataGenerator.generate_sym_mix_gauss(m,difference,angle)
		features_x.set_feature_matrix(array([data[0]]))
		features_y.set_feature_matrix(array([data[1]]))

		# re-create hsic instance everytime since feature objects are copied due to
		# useage of convienience constructor
		hsic=HSIC(kernel_x,kernel_y,features_x,features_y)
		alt_samples[i]=hsic.compute_statistic()

	# sample from null distribution
	# permutation, biased statistic
	hsic.set_null_approximation_method(PERMUTATION)
	hsic.set_num_null_samples(num_null_samples)
	null_samples_boot=hsic.sample_null()

	# fit gamma distribution, biased statistic
	hsic.set_null_approximation_method(HSIC_GAMMA)
	gamma_params=hsic.fit_null_gamma()
	# sample gamma with parameters
	null_samples_gamma=array([gamma(gamma_params[0], gamma_params[1]) for _ in range(num_null_samples)])

	# plot
	figure()

	# plot data x and y
	subplot(2,2,1)
	gca().xaxis.set_major_locator( MaxNLocator(nbins = 4) ) # reduce number of x-ticks
	gca().yaxis.set_major_locator( MaxNLocator(nbins = 4) ) # reduce number of x-ticks
	grid(True)
	plot(data[0], data[1], 'o')
	title('Data, rotation=$\pi$/'+str(1/angle*pi)+'\nm='+str(m))
	xlabel('$x$')
	ylabel('$y$')

	# compute threshold for test level
	alpha=0.05
	null_samples_boot.sort()
	null_samples_gamma.sort()
	thresh_boot=null_samples_boot[floor(len(null_samples_boot)*(1-alpha))];
	thresh_gamma=null_samples_gamma[floor(len(null_samples_gamma)*(1-alpha))];

	type_one_error_boot=sum(null_samples_boot<thresh_boot)/float(num_null_samples)
	type_one_error_gamma=sum(null_samples_gamma<thresh_boot)/float(num_null_samples)

	# plot alternative distribution with threshold
	subplot(2,2,2)
#.........这里部分代码省略.........