pandas :两个数据框的区别 [英] Pandas: Diff of two Dataframes

问题描述

我需要逐行比较两个大小不同的数据框，并打印出不匹配的行.让我们考虑以下两个:

I need to compare two dataframes of different size row-wise and print out non matching rows. Lets take the following two:

df1 = DataFrame({
'Buyer': ['Carl', 'Carl', 'Carl'],
'Quantity': [18, 3, 5, ]})

df2 = DataFrame({
'Buyer': ['Carl', 'Mark', 'Carl', 'Carl'],
'Quantity': [2, 1, 18, 5]})

在df2上按行打印并打印出不在df1中的行的最有效方法是什么，例如:

What is the most efficient way to row-wise over df2 and print out rows not in df1 e.g:

Buyer     Quantity 
Carl         2
Mark         1

重要:我不想有行:

Buyer     Quantity 
Carl         3

包含在差异中:

我已经尝试过: 比较两个不同长度的行，并为每行添加相等值的列 和在两个Pandas数据帧中输出差异并排-突出显示差异

I have already tried: Comparing two dataframes of different length row by row and adding columns for each row with equal value and Outputting difference in two Pandas dataframes side by side - highlighting the difference

但是这些与我的问题不匹配.

But these do not match with my problem.

谢谢

安迪

推荐答案

merge the 2 dfs using method 'outer' and pass param indicator=True this will tell you whether the rows are present in both/left only/right only, you can then filter the merged df after:

In [22]:
merged = df1.merge(df2, indicator=True, how='outer')
merged[merged['_merge'] == 'right_only']

Out[22]:
  Buyer  Quantity      _merge
3  Carl         2  right_only
4  Mark         1  right_only

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