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python - 如何为 pandas df 正确编写 if-then lambda 语句？

问题描述

我有以下代码：

data = [[11001218, 'Value', 93483.37, 'G', '', 93483.37, '', '56117J100', 'FRA', 'Equity'], 
        [11001218, 'Value', 3572.73, 'G', 3572.73, '', '56117J100', '', 'LUM', 'Equity'], 
        [11001218, 'Value', 89910.64, 'G', 89910.64, '', '56117J100', '', 'WAR', 'Equity'],
        [11005597, 'Value', 72640313.34,'L','',72640313.34, 'REVR21964', '','IN2',  'Repo']
       ]

df = pd.DataFrame(data, columns = ['ID', 'Type', 'Diff', 'Group', 'Amount','Amount2', 'Id2', 'Id3', 'Executor', 'Name'])

def logic_builder(row, row2, row3):
    if row['Name'] == 'Repo' and row['Group'] == 'L':
        return 'Fine resultant'
    elif (row['ID'] == row2['ID']) and (row['ID'] == row3['ID']) and (row['Group'] == row2['Group']) and (row['Group'] == row3['Group']) and (row['Executor'] != row2['Executor']) and (row['Executor'] != row3['Executor']):    
        return 'Difference in Executor'

df['Results'] = df.apply(lambda row: logic_builder(row, row2, row3), axis=1)

如果您查看前 3 行，它们在技术上都是相同的。它们包含相同的 ID、类型、组和名称。唯一的区别是执行者，因此我希望我的 if-then 语句返回“执行者的差异”。我无法弄清楚如何纠正 if-then 以查看我上面提到的字段的所有具有相似属性的行。

谢谢你。

标签： pythonpandasif-statementlambdaapply

解决方案

您可以传递单行，然后确定其索引并使用 查找其他行df.iloc[index]。

这里有一个例子

def logic_builder(row):
    global df #you need to access the df

    i = row.name #row index

    #get next rows
    try:
        row2 = df.iloc[i+1] 
        row3 = df.iloc[i+2]
    except IndexError:
        return
    
    if row['Name'] == 'Repo' and row['Group'] == 'L':
        return 'Fine resultant'
    elif (row['ID'] == row2['ID']) and (row['ID'] == row3['ID']) and (row['Group'] == row2['Group']) and (row['Group'] == row3['Group']) and (row['Executor'] != row2['Executor']) and (row['Executor'] != row3['Executor']):    
        return 'Difference in Executor'

df['Results'] = df.apply(logic_builder, axis=1)

当然，由于结果取决于接下来的两行，因此您不能在数据帧的最后两行上运行它。

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