根据后续变量更改变量

Question

我想重新格式化我的数据，以便如果一个人在呈阳性后又进行了阴性测试，则该阳性测试将更改为阴性（被视为假阳性）。

在我的数据集中，阳性测试在测试栏中用模棱两可、不确定或阳性表示。

library(tidyverse)
library(data.table)

date=c("2023-01-01", "2023-02-07", "2023-02-20","2023-01-01", "2023-02-07", "2023-02-20", "2023-01-01", "2023-05-10", "2023-01-01", "2023-01-01", "2023-01-01", "2023-01-01", "2023-01-01", "2023-01-01", "2023-01-10", "2023-01-01", "2023-01-10")
ID=c("A", "A", "A","A2", "A2", "A2", "B", "B", "C", "D", "D", "D1", "D1", "E", "E", "F", "F")
test=c("negative", "equivocal", "negative", "negative", "indeterminate", "negative", "negative", "negative", "positive", "positive", "negative","indeterminate", "negative", "positive", "negative", "negative", "positive")
df=as.data.table(cbind(date, ID, test))  
df[, date := as.Date(date)] 

因此，以下突出显示的测试将全部转换为阴性，因为在同一天或在阳性测试之后有阴性测试。

Answer 1

df[, test2 := df[.SD, 
                 on = .(ID, date >= date), 
                 if (any(test == "negative")) "negative" else test, 
                 by = .EACHI]$V1]

#           date     ID          test    test2
#         <Date> <char>        <char>   <char>
#  1: 2023-01-01      A      negative negative
#  2: 2023-02-07      A     equivocal negative
#  3: 2023-02-20      A      negative negative
#  4: 2023-01-01     A2      negative negative
#  5: 2023-02-07     A2 indeterminate negative
#  6: 2023-02-20     A2      negative negative
#  7: 2023-01-01      B      negative negative
#  8: 2023-05-10      B      negative negative
#  9: 2023-01-01      C      positive positive
# 10: 2023-01-01      D      positive negative
# 11: 2023-01-01      D      negative negative
# 12: 2023-01-01     D1 indeterminate negative
# 13: 2023-01-01     D1      negative negative
# 14: 2023-01-01      E      positive negative
# 15: 2023-01-10      E      negative negative
# 16: 2023-01-01      F      negative negative
# 17: 2023-01-10      F      positive positive