值的长度与使用np.linspace的熊猫的索引长度不匹配

Question

我正在尝试运行此代码，以便获得一张图表，其中x轴显示sigma的各种值，y轴显示利润的各种值

def price(cost,sigma):
    return cost*sigma
def profit(cost,sigma,expected_loss):
    return[(sigma-1)*cost-expected_loss]
sigmas=np.linspace(1,1000,endpoint=True,retstep=False,dtype=None,axis=0)
plt.figure()
for sigma in sigmas:
    df['profit']=profit(df['cost'],sigma,df['expected_loss'])
    df['i_price']=price(df['cost'],sigma)
    sum_profit=df.loc[df['risk_premium']>df['i_price'],'profit'].sum()
    plt.plot(sigma,sum_profit,color='green',marker='o',linestyle='solid')
plt.xlabel('sigma')
plt.ylabel('sum_profit')
plt.show()'