Christmas Bird Count history report system

# - - -   L u m p e d L a y o u t . _ _ i n i t _ _

    def __init__(self, effKeyList):
        '''Constructor.
        '''

The first order of business is to determine the set of keys. The cardinality of this set is the number of logical columns.

        #-- 1
        # [ self._keyList  :=  list of the unique year numbers
        #       in effKeyList, in ascending order
        #   self._nCols  :=  cardinality of that list ]
        self._keyList = sorted(set([ effKey.year_no
                                     for effKey in effKeyList ]))
        self._nCols = len(self._keyList)

The length of that list is the number of columns. Next, build the dictionary that maps effort keys to column numbers. This is essentially an inversion of the key list.

        #-- 2
        # [ self._keyColxMap  :=  as invariant ]
        self._keyColxMap = {}
        for colx in range(len(self._keyList)):
            self._keyColxMap[self._keyList[colx]] = colx

Count the number of years lumped into each column.

        #-- 3
        # [ self._yearCounts  :=  a list such that element [k]
        #       contains the number of effKeyList members whose
        #       year number goes into logical column [k] ]
        self._yearCounts = [0] * len(self._keyList)
        for effKey in effKeyList:
            colx = self._keyColxMap[effKey.year_no]
            self._yearCounts[colx] += 1