在Python中创建一个IF语句，以查看先前的IF语句输出 [英] Creating an IF statement in Python that looks at previous IF statement output

问题描述

我在创建执行以下操作的IF语句时遇到困难:

I am having difficulty creating an IF statement that does the following:

• 如果C1 =买入，则买入
• 如果C2 =卖出，则卖出
• 如果C1& C2 = nan，那么当前单元格=上一个单元格

请参见下面的示例.我希望创建一个像"C3"这样的列.

Please see an example below. I am hoping to create a column like 'C3'.

样本数据集:

index  C1    C2
0      Buy   nan
1      nan   nan
2      nan   Sell
3      nan   nan
4      Buy   nan
5      nan   Sell
6      nan   Sell
7      nan   nan
8      nan   nan
9      Buy   nan
10     nan   Sell

输出:

index  C1    C2    C3
0      Buy   nan   Buy
1      nan   nan   Buy
2      nan   Sell  Sell
3      nan   nan   Sell
4      Buy   nan   Buy
5      nan   Sell  Sell
6      nan   Sell  Sell
7      nan   nan   Sell
8      nan   nan   Sell
9      Buy   nan   Buy
10     nan   Sell  Sell

推荐答案

您可以使用 pd.DataFrame.ffill 和axis=1，后跟

You can use pd.DataFrame.ffill along axis=1 followed by pd.Series.ffill:

df['C3'] = df[['C1', 'C2']].ffill(axis=1).iloc[:, -1].ffill()

print(df)

    index   C1    C2    C3
0       0  Buy   NaN   Buy
1       1  NaN   NaN   Buy
2       2  NaN  Sell  Sell
3       3  NaN   NaN  Sell
4       4  Buy   NaN   Buy
5       5  NaN  Sell  Sell
6       6  NaN  Sell  Sell
7       7  NaN   NaN  Sell
8       8  NaN   NaN  Sell
9       9  Buy   NaN   Buy
10     10  NaN  Sell  Sell

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