# Implementation of the Histogram ADT using a Hash Map.

from hashmap import HashMap

class Histogram :
   # Creates a histogram containing the given categories.
  def __init__( self, catSeq ):
    self._freqCounts = HashMap()
    for cat in catSeq :
      self._freqCounts.add( cat, 0 )
    
   # Returns the frequency count for the given category.    
  def getCount( self, category ):
    assert category in self._freqCounts, "Invalid histogram category."
    return self._freqCounts.valueOf( category )
        
   # Increments the counter for the given category.
  def incCount( self, category ):
    assert category in self._freqCounts, "Invalid histogram category."
    value = self._freqCounts.valueOf( category )
    self._freqCounts.add( category, value + 1 )
      
   # Returns the sum of the frequency counts. 
  def totalCount( self ):
    total = 0
    for cat in self._freqCounts :
      total += self._freqCounts.valueOf( cat )
    return total
    
   # Returns an iterator for traversing the categories.
  def __iter__( self ):                        
    return iter( self._freqCounts )