Python 'NoneType' object has no attribute 'apply'

Question

#设定回撤值
withdraw = 0.03
#设定突破值
breakthrough =0.03
#设定账户资金
account = 10000
#持有仓位手数
position = 0

def buy(bar):
    global account,position
    print("{}: buy{}".format(bar.date,bar.close))
    #一手价格
    one = bar.close*100
    position = account//one
    account = account - (position*one)
    
def sell(bar):
    global account,position
    #一手价格
    print("{}:sell{}".format(bar.date,bar.close))
    one =bar.close*100
    account+=position*one
    position = 0
    
print("开始时间投资时间:",df.iloc[0]).apply(lambda x : x.days)
for date in df.index:
    bar = df.loc[date]
    if bar.pchange and bar.pchange > breakthrough and position ==0:
        buy(bar)
    elif bar.pchange and bar.pchange <withdraw and position > 0:
        sell(bar)
print("最终可有现金:",account)
print("最终持有市值:",position*df.iloc[-1].close*100)

Answer 1

print("开始时间投资时间:",df.iloc[0]).apply(lambda x : x.days)
改成
print("开始时间投资时间:",df.iloc[0].apply(lambda x : x.days))
.iloc[0] 之后的)移到后面