#!/usr/bin/python -Wall

# ================================================================
# John Kerl
# kerl at math dot arizona dot edu
# 2009-10-08
# Please see http://math.arizona.edu/~kerl/doc/python-talk.pdf for
# more information.
# ================================================================

import sys
import re

# ----------------------------------------------------------------
def text_columns_from_file(file_name):
	"""Given an input file containing tabular data, returns a list of columns.
	Pound signs may be used as comments; blank lines are skipped.
	For example, if the input file is

	1 2 3
	4 5 6 # Comment here

	7 8 9
	a b c

	then this routine returns
	[['1', '4', '7', 'a'], ['2', '5', '8', 'b'], ['3', '6', '9', 'c']].
	"""

	if (file_name == "-"):
		file_handle = sys.stdin
	else:
		try:
			file_handle = open(file_name, 'r')
		except:
			print >> sys.stderr, "Couldn't open \"" + file_name + "\" for read."
			sys.exit(1)

	columns     = []
	num_fields  = -1
	line_number =  0

	while 1:
		line = file_handle.readline()
		if (line == ""):
			break
		line_number += 1

		# Strip trailing carriage return, if any.
		if line[-1] == '\n':
			line = line[0:-1]
		# Strip comments.
		line = re.sub(r"#.*",  r"", line)
		# Strip leading and trailing whitespace.
		line = re.sub(r"^\s+", r"", line)
		line = re.sub(r"\s+$", r"", line)
		# Skip blank lines.
		if re.match(r"^$", line):
			continue

		# Split on whitespace.
		fields = line.split()
		curr_num_fields = len(fields)

		if (num_fields == -1):
			# First data line of file.
			num_fields = curr_num_fields
			for j in range(0, num_fields):
				columns.append([])
		elif curr_num_fields != num_fields:
			print >> sys.stderr, "Ragged input in file \"%s\" at line %d." % \
				(file_name, line_number)
			sys.exit(1)
		for j in range(0, num_fields):
			columns[j].append(fields[j])

	if (file_name != "-"):
		file_handle.close()

	return columns

# ----------------------------------------------------------------
def float_columns_from_file(file_name):
	"""Given an input file containing float tabular data, returns a list of columns.
	Pound signs may be used as comments; blank lines are skipped.
	For example, if the input file is

	1 2 3
	4 5 6 # Comment here

	7 8 9

	then this routine returns
	[[1.0, 4.0, 7.0], [2.0, 5.0, 8.0], [3.0, 6.0, 9.0]]
	"""

	columns = text_columns_from_file(file_name)
	num_rows = len(columns)
	num_cols = len(columns[0])
	for i in range(0, num_rows):
		for j in range(0, num_cols):
			columns[i][j] = float(columns[i][j])
	return columns

# ----------------------------------------------------------------
def float_columns_to_file(columns, file_name, format="%11.7f"):
	"""Given a list of columns, write the data to a table file.
	For example, if the input is

	[[1.0, 4.0, 7.0], [2.0, 5.0, 8.0], [3.0, 6.0, 9.0]]

	then the output file contains

	1.0000 2.0000 3.0000
	4.0000 5.0000 6.0000
	7.0000 8.0000 9.0000
	"""

	if (file_name == "-"):
		file_handle = sys.stdout
	else:
		try:
			file_handle = open(file_name, 'w')
		except:
			print >> sys.stderr, \
				"Couldn't open \"" + file_name + "\" for write."
			sys.exit(1)

	num_columns = len(columns)
	num_rows    = len(columns[0])
	for i in range(0, num_rows):
		for j in range(0, num_columns):
			print >> file_handle, format % columns[j][i],
		print >> file_handle, ""

	if (file_name != "-"):
		file_handle.close()