canonical-vs-non-canonical-01.py

class MFI(bt.Indicator):
    lines = ('mfi', 'money_flow_raw', 'typical', 'money_flow_pos', 'money_flow_neg')

    plotlines = dict(
        money_flow_raw=dict(_plotskip=True),
        money_flow_pos=dict(_plotskip=True),
        money_flow_neg=dict(_plotskip=True),
        typical=dict(_plotskip=True),
    )

    params = (
        ('period', 14),
    )

    def next(self):
        typical_price = (self.data.close[0] + self.data.low[0] + self.data.high[0]) / 3
        money_flow_raw = typical_price * self.data.volume[0]

        self.lines.typical[0] = typical_price
        self.lines.money_flow_raw[0] = money_flow_raw

        self.lines.money_flow_pos[0] = money_flow_raw if self.lines.typical[0] >= self.lines.typical[-1] else 0
        self.lines.money_flow_neg[0] = money_flow_raw if self.lines.typical[0] <= self.lines.typical[-1] else 0

        pos_period = math.fsum(self.lines.money_flow_pos.get(size=self.p.period))
        neg_period = math.fsum(self.lines.money_flow_neg.get(size=self.p.period))

        if neg_period == 0:
            self.lines.mfi[0] = 100
            return

        self.lines.mfi[0] =  100 - 100 / (1 +  pos_period / neg_period)