python - 需要迭代行以检查条件并在满足条件时从不同列检索值

Question

我有股票的每日价格数据。粘贴最后 31 行数据作为示例数据集，如下所示:

       Date         RSI         Smooth          max         min
110  2019-02-13   38.506874  224.006543         NaN         NaN
111  2019-02-14   39.567068  227.309923         NaN         NaN
112  2019-02-15   43.774479  229.830776         NaN         NaN
113  2019-02-18   43.651440  231.690179         NaN         NaN
114  2019-02-19   43.467237  232.701976         NaN         NaN
115  2019-02-20   44.370123  233.526131         NaN         NaN
116  2019-02-21   45.605073  233.834988  233.834988         NaN
117  2019-02-22   46.837518  232.335179         NaN         NaN
118  2019-02-25   42.087860  229.570711         NaN         NaN
119  2019-02-26   39.008014  226.379526         NaN         NaN
120  2019-02-27   39.542339  225.607475         NaN  225.607475
121  2019-02-28   39.051104  228.305615         NaN         NaN
122  2019-03-01   48.191687  232.544289         NaN         NaN
123  2019-03-05   51.909527  237.063534         NaN         NaN
124  2019-03-06   52.988668  240.243201         NaN         NaN
125  2019-03-07   54.205990  242.265173         NaN         NaN
126  2019-03-08   54.967076  243.912033         NaN         NaN
127  2019-03-11   58.080738  244.432163  244.432163         NaN
128  2019-03-12   55.587328  243.573710         NaN         NaN
129  2019-03-13   51.714123  241.191933         NaN         NaN
130  2019-03-14   48.948075  238.470485         NaN         NaN
131  2019-03-15   46.615111  236.144640         NaN         NaN
132  2019-03-18   48.219815  233.588265         NaN         NaN
133  2019-03-19   41.866898  230.271903         NaN  230.271903
134  2019-03-20   34.818844  239.457110         NaN         NaN
135  2019-03-22   42.167870  246.824173         NaN         NaN
136  2019-03-25   60.228588  255.294124         NaN         NaN
137  2019-03-26   66.896640  267.069173         NaN         NaN
138  2019-03-27   68.823285  278.222343         NaN         NaN
139  2019-03-28   63.654023  289.042091  289.042091         NaN

我正在尝试开发代码逻辑，如下所示:如果 max > 0，则搜索前一个非零最大值并将其分配给 max2。另外，将先前非零最大值对应的 RSI 指定为 RSI2。

期望的输出:对于数据集中的第 139 行，max2 将为 244.432163，RSI2 将为 58.080738对于数据集中的第 138 行，max2 将为 0，RSI 2 将为 0，依此类推...

我尝试了不同的方法，但没有成功获得任何输出，因此我没有可粘贴的示例代码。

我也尝试过使用 if 循环，但无法使其工作。我对编程很陌生。

Answer 1

首先您需要iterate the dataframe .

然后您将需要存储下一次点击时需要保存的先前值。由于您总是会返回到之前的最大值，因此您可以在循环时重复使用它。

像这样的东西(没有测试，只是为了一个想法):

last_max = 0   
last_rsi = 0
for index, row in df.iterrows():
    if row['max']:
        row['max2'] = last_max
        row['rsi2'] = last_rsi
        last_max = row['max']   # store this max/rsi for next time
        last_rsi = row['rsi']