libsvm2csv.py

import sys, csv
import argparse

parser = argparse.ArgumentParser(description = 'convert libsvm file to csv')
parser.add_argument("input_file", help = "path to csv input file")
parser.add_argument("output_file", help = "path to output file")
parser.add_argument("dimensionality", type = int, help = "dimensionality of feature set")

args = parser.parse_args()

d = args.dimensionality
assert ( d > 0 )

reader = csv.reader( open( args.input_file ), delimiter = " " )
writer = csv.writer( open( args.output_file, 'wb' ))

for line in reader:
	label = line.pop( 0 )
	if line[-1].strip() == '':
		line.pop( -1 )

	# print line

	line = map( lambda x: tuple( x.split( ":" )), line )
	#print line
	# ('1', '0.194035105364'), ('2', '0.186042408882'), ('3', '-0.148706067206'), ...

	new_line = [ label ] + [ 0 ] * d
	for i, v in line:
		i = int( i )
		if i <= d:
			new_line[i] = v

	writer.writerow( new_line )