(self)
return npv
NPV curve

        The first value is undefined (no negative instances). To avoid this,
        we copy the second value into the first.
NPV curve
NPV curve
def npv(self):
        """
        NPV curve

        The first value is undefined (no negative instances). To avoid this,
        we copy the second value into the first.
        """
        tn_fn = np.arange(self.tot + 1)
        tn_fn[0] = 1  # avoid division by zero
        npv = self.tn / tn_fn
        npv[0] = npv[1]
        return npv
def npv ( self ) : tn_fn = np . arange ( self . tot + 1 ) tn_fn [ 0 ] = 1 # avoid division by zero npv = self . tn / tn_fn npv [ 0 ] = npv [ 1 ] return npv