r - 如何计算R中 bool 数据的组合数

Question

确定因素或基于许多 bool 字段创建新类别字段的最佳方法是什么？在此示例中，我需要计算药物的唯一组合数。

   > MultPsychMeds
       ID OLANZAPINE HALOPERIDOL QUETIAPINE RISPERIDONE
    1   A          1           1          0           0
    2   B          1           0          1           0
    3   C          1           0          1           0
    4   D          1           0          1           0
    5   E          1           0          0           1
    6   F          1           0          0           1
    7   G          1           0          0           1
    8   H          1           0          0           1
    9   I          0           1          1           0
    10  J          0           1          1           0

也许另一种表达方式是我需要对或对列表进行交叉或交叉制表。最终结果应类似于:

Combination            Count
OLANZAPINE/HALOPERIDOL     1
OLANZAPINE/QUETIAPINE      3
OLANZAPINE/RISPERIDONE     4
HALOPERIDOL/QUETIAPINE     2

可以使用以下命令在R中复制此数据帧:

MultPsychMeds <- structure(list(ID = structure(1:10, .Label = c("A", "B", "C", 
"D", "E", "F", "G", "H", "I", "J"), class = "factor"), OLANZAPINE = c(1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 0L, 0L), HALOPERIDOL = c(1L, 0L, 
0L, 0L, 0L, 0L, 0L, 0L, 1L, 1L), QUETIAPINE = c(0L, 1L, 1L, 1L, 
0L, 0L, 0L, 0L, 1L, 1L), RISPERIDONE = c(0L, 0L, 0L, 0L, 1L, 
1L, 1L, 1L, 0L, 0L)), .Names = c("ID", "OLANZAPINE", "HALOPERIDOL", 
"QUETIAPINE", "RISPERIDONE"), class = "data.frame", row.names = c(NA, 
-10L))

Answer 1

这是使用reshape和plyr包的一种方法:

library(reshape)
library(plyr)

#Melt into long format
dat.m <- melt(MultPsychMeds, id.vars = "ID")
#Group at the ID level and paste the drugs together with "/"
out <- ddply(dat.m, "ID", summarize, combos = paste(variable[value == 1], collapse = "/"))

#Calculate a table
with(out, count(combos))

                       x freq
1 HALOPERIDOL/QUETIAPINE    2
2 OLANZAPINE/HALOPERIDOL    1
3  OLANZAPINE/QUETIAPINE    3
4 OLANZAPINE/RISPERIDONE    4