annotate LocationFile.py @ 0:32f8fbdd754c default tip

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author rico
date Fri, 06 Apr 2012 13:59:29 -0400
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1 #!/usr/bin/env python
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2
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3 import sys
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4
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5 def die( message ):
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6 print >> sys.stderr, message
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7 sys.exit(1)
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8
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9 def open_or_die( filename, mode='r', message=None ):
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10 if message is None:
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11 message = 'Error opening {0}'.format( filename )
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12 try:
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13 fh = open( filename, mode )
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14 except IOError, err:
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15 die( '{0}: {1}'.format( message, err.strerror ) )
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16 return fh
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17
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18 class LocationFile( object ):
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19 def __init__( self, filename, comment_chars=None, delimiter='\t', key_column=0 ):
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20 self.filename = filename
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21 if comment_chars is None:
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22 self.comment_chars = ( '#' )
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23 else:
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24 self.comment_chars = tuple( comment_chars )
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25 self.delimiter = delimiter
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26 self.key_column = key_column
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27 self._map = {}
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28 self._populate_map()
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29
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30 def _populate_map( self ):
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31 try:
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32 with open( self.filename ) as fh:
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33 line_number = 0
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34 for line in fh:
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35 line_number += 1
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36 line = line.rstrip( '\r\n' )
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37 if not line.startswith( self.comment_chars ):
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38 elems = line.split( self.delimiter )
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39 if len( elems ) <= self.key_column:
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40 die( 'Location file {0} line {1}: less than {2} columns'.format( self.filename, line_number, self.key_column + 1 ) )
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41 else:
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42 key = elems.pop( self.key_column )
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43 if key in self._map:
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44 if self._map[key] != elems:
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45 die( 'Location file {0} line {1}: duplicate key "{2}"'.format( self.filename, line_number, key ) )
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46 else:
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47 self._map[key] = elems
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48 except IOError, err:
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49 die( 'Error opening location file {0}: {1}'.format( self.filename, err.strerror ) )
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50
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51 def get_values( self, key ):
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52 if key in self._map:
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53 rval = self._map[key]
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54 if len( rval ) == 1:
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55 return rval[0]
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56 else:
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57 return rval
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58 else:
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59 die( 'key "{0}" not found in location file {1}'.format( key, self.filename ) )