Christmas Bird Count history report system

# - - -   P a r t y H o u r s R o w . _ s u m E f f o r t s

    def _sumEfforts(self):
        '''Return all column efforts as a list of LabelCell instances

          [ return a list of PartyHoursCell instances, one per logical
            column, where each instance displays the total number
            of party-hours from the self.db.Effort table for that
            column ]
        '''

We start with the list of effort keys from self.cbcHist.effKeyList. For each such key, we determine which logical column it belongs to, and add it to a list of float values.

        #-- 1
        # [ cellList  :=  a list containing self.cbcHist.nCols
        #                PartyHoursCell instances ]
        cellList = [ PartyHoursCell()
                    for k in range(self.cbcHist.nCols) ]

Only positive values are added to each cell. This is important so that zero or negative party-hours values from the database are not used for statistical calculations.

        #-- 2
        # [ cellList  :=  cellList with party-hours added from
        #       self.cbcHist.db's Effort instances for effort keys
        #       in self.cbcHist.effKeyList ]
        for effKey in self.cbcHist.effKeyList:
            effort = self.cbcHist.db.getEffort(effKey.year_no,
                         effKey.year_key)
            value = float(effort.ph_tot)
            colx = self.cbcHist.findColumn(effKey)
            if value > 0.0:
                cellList[colx].add(value)

        #-- 3
        return cellList