根据特定条件将行转换为列

Question

我有一个包含属性及其对应值的数据集，如下所示

 Obs#     Id     Class   Date            MedicationName        Dose        BloodTestResult
 1        1433   1       2007/01/01      Sitaglyptin           100mg       6.2
 2        1433   1       2007/03/24      Sitaglyptin           100mg       6.4
 3        1433   1       2007/06/15      Sitaglyptin           100mg       6.5
 4        1433   2       2007/09/25      Glucophage            10mg        6.7
 5        1433   2       2007/12/30      Glucophage            10mg        6.5
 6        1433   2       2008/02/01      Glucophage            10mg        6.6
 7        1433   3       2008/05/03      Glumetza              10mg        7.2
 8        1433   3       2008/08/10      Glumetza              10mg        6.4
 9        1433   3       2008/11/14      Glumetza              20mg        6.7
10        1433   3       2009/02/02      Glumetza              20mg        6.5
11        8348   3       2007/04/11      Glumetza              20mg        6.5
12        8348   3       2007/07/15      Glumetza              20mg        6.6

我喜欢把它转换成这样的数据集

 Obs#     Id     Class  Date1       MedicationName1       Dose1      Date2           MedicationName2       Dose2      Date3           MedicationName3       Dose3      BloodTestResult
 1        1433   1      2007/01/01  Sitaglyptin           100mg      2007/03/24      Sitaglyptin           100mg      2007/09/25      Glucophage            100mg        6.7
 2        1433   2      2007/09/25  Glucophage            10mg       2007/12/30      Glucophage            10mg       2008/02/01      Glucophage            10mg         7.2
 3        1433   3      2008/05/03  Glumetza              10mg       2008/08/10      Glumetza              10mg         -                 -                 -            6.7
 4        1433   3      2008/11/14  Glumetza              20mg       2009/02/02      Glumetza              20mg         -                 -                 -            6.5
 5        8348   3      2007/04/11  Glumetza              20mg       2007/07/15      Glumetza              20mg         -                 -                 -            6.6

上面的数据集根据这些条件中的任何一个从行转换为列。

场景 1) 改变药物 (MedicantionName) 或改变剂量 (Dose)

    Observations 1,2,3 are same Medications (Sitaglyptin) and same dose (100mg). 
    So these three rows (1,2,3) are transformed into one row (row 1) as 
    shown in the tranformed dataset and
    The last column BloodTestResults will contain the value from 4th row (6.7).

    Similarly rows 4,5,6 because of Medication change(Glucophage). These 
    three rows 4,5,6  are transformed to a single row 2 as shown in the new  
    dataset and  
    The last column BloodTestResults will contain the value from 7th row (7.2).

    Similarly rows 7 and 8 because of Medication change (Glumetza). These 
    two rows 7,8  are transformed to a single row 3 as shown in the new 
    dataset and 
    The last column BloodTestResults will contain the value from 9th row (6.7).

场景 2) 改变药物 (MedicantionName) 或改变剂量 (Dose)

    Rows 9, 10 are transformed to a single row 4 as shown in the new dataset 
    because of dosage change(20mg) and 
    The last column BloodTestResults will contain the value from 10th row 
    (6.5) and not 11th row because this is the last   
    medication/dosage change for the id 1433

场景 3) 该患者 ID 记录的最后一次用药

    Rows 11,12 represent the only or last available information regarding
    id 8348. So they are just transformed to single row 5 as shown in the
    transformed dataset and
    The last column BloodTestResults will contain the value from 12th row 
    (6.6) because this is the last   
    medication/dosage change for the id 8348

如果出现混乱，我深表歉意，希望我已经清楚地解释了转换此数据集的模式。感谢根据这些要求转换此数据集的任何帮助。

数据

df <- structure(list(Obs = 1:12, Id = c(1433L, 1433L, 1433L, 1433L, 
1433L, 1433L, 1433L, 1433L, 1433L, 1433L, 8348L, 8348L), Class = c(1L, 
1L, 1L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L), Date = structure(c(1L, 
2L, 4L, 6L, 7L, 8L, 9L, 10L, 11L, 12L, 3L, 5L), .Label = c("2007/01/01", 
"2007/03/24", "2007/04/11", "2007/06/15", "2007/07/15", "2007/09/25", 
"2007/12/30", "2008/02/01", "2008/05/03", "2008/08/10", "2008/11/14", 
"2009/02/02"), class = "factor"), MedicationName = structure(c(3L, 
3L, 3L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("Glucophage", 
"Glumetza", "Sitaglyptin"), class = "factor"), Dose = structure(c(1L, 
1L, 1L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L), .Label = c("100mg", 
"10mg", "20mg"), class = "factor"), BloodTestResult = c(6.2, 
6.4, 6.5, 6.7, 6.5, 6.6, 7.2, 6.4, 6.7, 6.5, 6.5, 6.6)), .Names = c("Obs", 
"Id", "Class", "Date", "MedicationName", "Dose", "BloodTestResult"
), class = "data.frame", row.names = c(NA, -12L))

Answer 1

这是一种棘手的数据转换，尤其是 BloodTestResult，因为它需要 Id、Class（或 MedicationName）和 Dose 初始分组之外的数据。将其分解为步骤，您可以尝试以下操作，（我将数据称为dat）

## First split data: Id, Class and Dose
groups <- split(dat, interaction(dat$Id, dat$Class, dat$Dose, drop=T))

## Then, for each grouping, split by rows the columns you want to expand
tmp <- lapply(groups, function(x)
    cbind(x[1,1:3], do.call(cbind, split(x[,-c(1:3, ncol(x))], 1:nrow(x)))))

## Put back into data.frame
library(plyr)  # for rbind.fill, since some data.frames are missing columns
res <- do.call(rbind.fill, tmp)

## Finally, add the bloodtest
res$BloodTestResult <- unlist(sapply(split(dat, dat$Id), function(x)
    c(x$BloodTestResult[c(F, !(tail(x$Dose, -1) == head(x$Dose, -1) &
                                 tail(x$Class, -1) == head(x$Class, -1)))],
      tail(x$BloodTestResult, 1))))

#   Obs   Id Class     1.Date 1.MedicationName 1.Dose     2.Date 2.MedicationName
# 1   1 1433     1 2007/01/01      Sitaglyptin  100mg 2007/03/24      Sitaglyptin
# 2   4 1433     2 2007/09/25       Glucophage   10mg 2007/12/30       Glucophage
# 3   7 1433     3 2008/05/03         Glumetza   10mg 2008/08/10         Glumetza
# 4   9 1433     3 2008/11/14         Glumetza   20mg 2009/02/02         Glumetza
# 5  11 8348     3 2007/04/11         Glumetza   20mg 2007/07/15         Glumetza
#   2.Dose     3.Date 3.MedicationName 3.Dose BloodTestResult
# 1  100mg 2007/06/15      Sitaglyptin  100mg             6.7
# 2   10mg 2008/02/01       Glucophage   10mg             7.2
# 3   10mg       <NA>             <NA>   <NA>             6.7
# 4   20mg       <NA>             <NA>   <NA>             6.5
# 5   20mg       <NA>             <NA>   <NA>             6.6

BloodTest 列的计算方法是首先按 Id 拆分数据，然后查找 Dose 或 Class 的变化，并在这些位置提取 BloodTestResult，然后结合每个 Id 的最后一个 BloodTestValue。