识别和删除 R 中的反向事务

Question

我有一个超过 400,000 行的 dataframe，范围从 2020 年 1 月到 2020 年 12 月，以下是三个月的片段：

 tab <- structure(list(Date = structure(c(1580947200, 1581033600, 1581120000, 
1581206400, 1581292800, 1581379200, 1581465600, 1581552000, 1581638400, 
1583798400, 1583884800, 1583971200, 1584057600, 1584144000, 1584230400, 
1584316800, 1584403200, 1587168000, 1587254400, 1587340800, 1587427200, 
1587513600, 1587600000, 1587686400), class = c("POSIXct", "POSIXt"
), tzone = "UTC"), `Product Type` = c("LIZX", "LIZX", "LIZX", 
"LIZX", "LIZX", "LIZX", "LIZX", "LIZX", "LIZX", "LIZX", "LIZX", 
"LIZX", "LIZX", "LIZX", "LIZX", "LIZX", "LIZX", "LIZX", "LIZX", 
"LIZX", "LIZX", "LIZX", "LIZX", "LIZX"), Account = c(931, 931, 
931, 931, 931, 931, 931, 931, 931, 931, 931, 931, 931, 931, 931, 
931, 931, 931, 931, 931, 931, 931, 931, 931), Subsidiary = c(124, 
124, 124, 124, 124, 124, 124, 124, 124, 124, 124, 124, 124, 124, 
124, 124, 124, 124, 124, 124, 124, 124, 124, 124), Description = c("Transaction", 
"Transaction X", "Transaction", "Transaction", "Transaction X", 
"Transaction", "Transaction", "Transaction", "Transaction", "Transaction", 
"Transaction", "Transaction", "Transaction", "Transaction", "Transaction", 
"Transaction", "Transaction", "Transaction", "Transaction", "Transaction", 
"Transaction", "Transaction", "Transaction", "Transaction"), 
    `Policy Number` = c(42057926, 42057926, 42057926, 42057926, 
    42057926, 42057926, 42057926, 42057926, 42057926, 42060466, 
    42060466, 42060466, 42060466, 42060466, 42060466, 42060466, 
    42060466, 42060467, 42060467, 42060467, 42060467, 42060467, 
    42060467, 42060467), Amount = c(10, -10, 20, -20, 30, 24, 
    23, 22, -0.56, 1, -1, 2, -2, 2, 3, 4, -1, 3, -3, -3, -3, 
    -3, -3, -3)), row.names = c(NA, -24L), class = c("tbl_df", 
"tbl", "data.frame"))

对于某些保单（以保单编号表示），存在冲销交易，在同一个月，完全相同的金额作为正数记入借方，然后作为负数移除，反之亦然。

本质上，我想识别并从 dataframe 中删除所有此类逆转。 请注意，反向交易对并不总是在相邻的行中。

我已尝试遵循此相关帖子中给出的建议，但它似乎并没有解决这种特定类型的 dataframe。 我遇到的最大问题是，当我尝试根据保单编号和金额识别重复项时，所有重复项都被标记，而不仅仅是一对。

例如，对于策略 42060467，在同一个月内有 6 笔（-3）的交易和 1 笔（3）的交易。 因此，我想删除一 (-3) 笔交易和一 (3) 笔交易，留下 5 (3) 笔交易。

对此的任何建议将不胜感激！