如何加速/替换python for循环

Question

我正在运行以下代码：

def get_previous_next_returns(portfolio,total_returns):
    assets=[]
    i=0
    for asset in portfolio:
        i+=1
        try:
            for offset in [1,5,15,30,45,60,75,90,120,150,
                           200,250,500,750,1000,1250,1500]:
                print(i,asset.name,offset)
                asset['return_stock'] = (asset.Close - asset.Close.shift(1)) / (asset.Close.shift(1))
                merged_data = pd.merge(asset, sp_500, on='Date')
                total_positive_days=0
                total_beating_sp_days=0
                total_days = offset
                for index in range(0,len(merged_data)):
                    if index-offset>0:
                #for index, row in merged_data.iterrows():
                    #print(offset, index)
                        sliced = merged_data.iloc[index - offset : index]
                        total_positive_days = (sliced.Close_x > sliced.Close_x.shift(1)).sum()
                        total_beating_sp_days = (sliced.return_stock > sliced.return_sp).sum()
                        percentage_of_positive_days = float(total_positive_days/total_days)
                        percentage_of_beating_days = float(total_beating_sp_days/total_days)
                        asset.loc[index,'Pct_positive_'+str(offset)] = percentage_of_positive_days
                        asset.loc[index,'Pct_beating_'+str(offset)] = percentage_of_beating_days
                # previous period returns
                asset['Pct_change_'+str(offset)] = asset['Close'].pct_change(periods = offset)
                # next period returns
                asset['Pct_change_plus_'+str(offset)] = asset['Close'].pct_change(periods = -offset)
            assets.append(asset)
            total_returns=total_returns.append(asset) 
        except IndexError:
            print("Index error")
    return assets, total_returns

问题是我运行它的数据帧（合并的数据）非常大（超过一百万行），因此代码需要很多小时才能完成。。。有没有办法加快它的速度（即用更有效的代码块重新协调for循环）？你知道吗

Answer 1

将数据帧划分为多个部分，并使用python的多处理模块并行执行它们。 你可以用多处理池或者多处理过程为此目的