New translations subset.py (Chinese Simplified)

lang/zh/gklearn/gedlib/lib/libsvm.3.22/tools/subset.py

@@ -0,0 +1,120 @@
+#!/usr/bin/env python
+
+import os, sys, math, random
+from collections import defaultdict
+
+if sys.version_info[0] >= 3:
+	xrange = range
+
+def exit_with_help(argv):
+	print("""\
+Usage: {0} [options] dataset subset_size [output1] [output2]
+
+This script randomly selects a subset of the dataset.
+
+options:
+-s method : method of selection (default 0)
+     0 -- stratified selection (classification only)
+     1 -- random selection
+
+output1 : the subset (optional)
+output2 : rest of the data (optional)
+If output1 is omitted, the subset will be printed on the screen.""".format(argv[0]))
+	exit(1)
+
+def process_options(argv):
+	argc = len(argv)
+	if argc < 3:
+		exit_with_help(argv)
+
+	# default method is stratified selection
+	method = 0  
+	subset_file = sys.stdout
+	rest_file = None
+
+	i = 1
+	while i < argc:
+		if argv[i][0] != "-":
+			break
+		if argv[i] == "-s":
+			i = i + 1
+			method = int(argv[i])
+			if method not in [0,1]:
+				print("Unknown selection method {0}".format(method))
+				exit_with_help(argv)
+		i = i + 1
+
+	dataset = argv[i]
+	subset_size = int(argv[i+1])
+	if i+2 < argc:
+		subset_file = open(argv[i+2],'w')
+	if i+3 < argc:
+		rest_file = open(argv[i+3],'w')
+
+	return dataset, subset_size, method, subset_file, rest_file
+
+def random_selection(dataset, subset_size):
+	l = sum(1 for line in open(dataset,'r'))
+	return sorted(random.sample(xrange(l), subset_size))
+
+def stratified_selection(dataset, subset_size):
+	labels = [line.split(None,1)[0] for line in open(dataset)]
+	label_linenums = defaultdict(list)
+	for i, label in enumerate(labels):
+		label_linenums[label] += [i]
+
+	l = len(labels)
+	remaining = subset_size
+	ret = []
+
+	# classes with fewer data are sampled first; otherwise
+	# some rare classes may not be selected
+	for label in sorted(label_linenums, key=lambda x: len(label_linenums[x])):
+		linenums = label_linenums[label]
+		label_size = len(linenums) 
+		# at least one instance per class
+		s = int(min(remaining, max(1, math.ceil(label_size*(float(subset_size)/l)))))
+		if s == 0:
+			sys.stderr.write('''\
+Error: failed to have at least one instance per class
+    1. You may have regression data.
+    2. Your classification data is unbalanced or too small.
+Please use -s 1.
+''')
+			sys.exit(-1)
+		remaining -= s
+		ret += [linenums[i] for i in random.sample(xrange(label_size), s)]
+	return sorted(ret)
+
+def main(argv=sys.argv):
+	dataset, subset_size, method, subset_file, rest_file = process_options(argv)
+	#uncomment the following line to fix the random seed 
+	#random.seed(0)
+	selected_lines = []
+
+	if method == 0:
+		selected_lines = stratified_selection(dataset, subset_size)
+	elif method == 1:
+		selected_lines = random_selection(dataset, subset_size)
+
+	#select instances based on selected_lines
+	dataset = open(dataset,'r')
+	prev_selected_linenum = -1
+	for i in xrange(len(selected_lines)):
+		for cnt in xrange(selected_lines[i]-prev_selected_linenum-1):
+			line = dataset.readline()
+			if rest_file: 
+				rest_file.write(line)
+		subset_file.write(dataset.readline())
+		prev_selected_linenum = selected_lines[i]
+	subset_file.close()
+
+	if rest_file:
+		for line in dataset: 
+			rest_file.write(line)
+		rest_file.close()
+	dataset.close()
+
+if __name__ == '__main__':
+	main(sys.argv)
+