r - 如何在两个 data.tables(或 data.frames)的行之间创建随机匹配

Question

对于这个例子，我将使用 data.table包裹。

假设你有一张教练 table

coaches <- data.table(CoachID=c(1,2,3), CoachName=c("Bob","Sue","John"), NumPlayers=c(2,3,0))
coaches
   CoachID CoachName NumPlayers
1:       1       Bob          2
2:       2       Sue          3
3:       3      John          0

和一 table 玩家

players <- data.table(PlayerID=c(1,2,3,4,5,6), PlayerName=c("Abe","Bart","Chad","Dalton","Egor","Frank"))
players
   PlayerID PlayerName
1:        1        Abe
2:        2       Bart
3:        3       Chad
4:        4     Dalton
5:        5       Egor
6:        6      Frank

您希望将每个教练与一组球员相匹配，这样

与每个教练相关的球员人数由 NumPlayers 字段

定义。

没有两个教练与同一个球员联系在一起

球员和教练随机匹配

你这是怎么做到的？

exampleResult <- data.table(CoachID=c(1,1,2,2,2,3), PlayerID=c(3,1,2,5,6,NA))
exampleResult

   CoachID PlayerID
1:       1        3
2:       1        1
3:       2        2
4:       2        5
5:       2        6
6:       3       NA

Answer 1

您可以从玩家 ID 中采样而无需替换，获取您需要的玩家总数:

set.seed(144)
(selections <- sample(players$PlayerID, sum(coaches$NumPlayers)))
# [1] 1 4 3 2 6

每个玩家将有相同的概率被包含在 selections 中，并且该向量的顺序是随机的。因此，您可以将这些球员分配到每个教练位置:

data.frame(CoachID=rep(coaches$CoachID, coaches$NumPlayers),
           PlayerID=selections)
#   CoachID PlayerID
# 1       1        1
# 2       1        4
# 3       2        3
# 4       2        2
# 5       2        6

如果您想拥有 NA对于没有球员选择的任何教练的值(value)，您可以执行以下操作:

rbind(data.frame(CoachID=rep(coaches$CoachID, coaches$NumPlayers),
                 PlayerID=selections),
      data.frame(CoachID=coaches$CoachID[coaches$NumPlayers==0],
                 PlayerID=rep(NA, sum(coaches$NumPlayers==0))))
#   CoachID PlayerID
# 1       1        1
# 2       1        4
# 3       2        3
# 4       2        2
# 5       2        6
# 6       3       NA