Dictionary holding colors that correspond to constraints.

def colordict(self):
        """
        Dictionary holding colors that correspond to constraints.
        """
        d = {}
        i=0
        n = len(self.constraints)
        for c in self.constraints:
            #self.colordict[c] = colors[i % 6]
            d[c] = cm.jet(1.*i/n)
            i+=1
        return d