寻找每个患者最接近的匹配时间

我有两组数据：

第一组：

 patient<-c("A","A","B","B","C","C","C","C")
 arrival<-c("11:00","11:00","13:00","13:00","14:00","14:00","14:00","14:00")
 lastRow<-c("","Yes","","Yes","","","","Yes")

 data1<-data.frame(patient,arrival,lastRow)

另一组数据：

 patient<-c("A","A","A","A","B","B","B","C","C","C")
 availableSlot<-c("11:15","11:35","11:45","11:55","12:55","13:55","14:00","14:00","14:10","17:00")

 data2<-data.frame(patient, availableSlot)

我想在第一个数据集中添加一列，以便对于每个患者的最后一行，它显示可用的插槽 最接近到达时间：

结果将是：

  patient arrival lastRow availableSlot
       A   11:00        
       A   11:00     Yes     11:15
       B   13:00        
       B   13:00     Yes     12:55
       C   14:00        
       C   14:00        
       C   14:00        
       C   14:00     Yes     14:00

如果有人能告诉我如何在 R 中实现这一点，我将不胜感激。

我会使用 data.table，首先通过转换为 ITime 并忽略冗余行来进行清理：

library(data.table)
setDT(data1)[, arrival := as.ITime(as.character(arrival))]
setDT(data2)[, availableSlot := as.ITime(as.character(availableSlot))]
DT1 = unique(data1, by="patient", fromLast=TRUE)

然后你可以做一个“滚动连接”：

res = data2[DT1, on=.(patient, availableSlot = arrival), roll="nearest", 
  .(patient, availableSlot = x.availableSlot)]

#    patient availableSlot
# 1:       A      11:15:00
# 2:       B      12:55:00
# 3:       C      14:00:00

怎么运行的

语法是x[i, on=, roll=, j].

• on=是合并列。
• 这是一个连接：对于每一行i，我们正在寻找匹配项x.
• With roll="nearest"，最后一列on=被“滚动”到最接近的匹配项。
• The on=原始表中的列可以引用x.* and i.*前缀。
• The j参数应该给出一个列列表，并且.()是一个别名list() here.

查看该包的介绍材料：http://r-datatable.com/Getting-started并输入?data.table与滚动连接相关的文档。

我会停在res，但如果你真的想把它放回到原来的表中......

# a very nonstandard step:
data1[lastRow == "Yes", availableSlot := res$availableSlot ]

#    patient  arrival lastRow availableSlot
# 1:       A 11:00:00                  <NA>
# 2:       A 11:00:00     Yes      11:15:00
# 3:       B 13:00:00                  <NA>
# 4:       B 13:00:00     Yes      12:55:00
# 5:       C 14:00:00                  <NA>
# 6:       C 14:00:00                  <NA>
# 7:       C 14:00:00                  <NA>
# 8:       C 14:00:00     Yes      14:00:00

Now, data1 has availableSlot在新列中，类似于您执行的操作data1$col <- val.