如何在R中重塑一个data.frame而没有循环？

我在R有一个data.frame我需要比较两行数据，如果它们是相同的，我需要合并行并将数据合并到一列中。我觉得这是一个共同的需要，当使用R所以使用ddply或其他包应该能够完成这项任务。下面是数据原样，dat，它在一些代码后应该是什么样的，foo.我是新来的，所以任何帮助都非常感谢。如何在R中重塑一个data.frame而没有循环？

前：

dat <- structure(list(detected_id = c(11, 11, 4), reviewer_name = c("mike", 
"mike", "john"), created_at = c("2016-05-04 10:02:45", "2016-05-04 10:02:45", 
"2016-05-04 10:02:45"), stage = c(2L, 2L, 1L), V7 = c("Detected Organism: Staphylococcus Aureus, Comment: Looks good", 
"Detected Organism: Staphylococcus Aureus, Comment: Note 1", 
"Detected Organism: Human Adenovirus 7, Comment: test")), .Names = c("detected_id", 
"reviewer_name", "created_at", "stage", "V7"), row.names = c(NA, 
-3L), class = "data.frame")

后：

foo <- structure(list(detected_id = c(11L, 4L), reviewer_name = c("mike", 
"john"), created_at = structure(c(1L, 1L), .Label = "5/4/16 10:02", class = "factor"), 
    stage = c(2L, 1L), V7 = structure(c(2L, 1L), .Label = c("Detected Organism: Human Adenovirus 7, Comment: test", 
    "Detected Organism: Staphylococcus Aureus, Comment: Looks good; Detected Organism: Staphylococcus Aureus, Comment: Note 1" 
    ), class = "factor")), .Names = c("detected_id", "reviewer_name", 
"created_at", "stage", "V7"), row.names = c(NA, -2L), class = "data.frame")

编辑：

下面我提供的数据集工作的解决方案，但我发现的情况下，这些解决方案实际上并不像预期的那样工作。这是失败的data.frame的一个例子。请注意，detected_id列对我来说已经过时了。

dat <- structure(list(detected_id = c(11, 11, 11, 11, 12, 4), reviewer_name = c("Mike", 
"Mike", "Mike", "Mike", "John", "John"), created_at = c("2016-05-04 10:02:45", 
"2016-05-04 10:02:45", "2016-05-04 10:02:45", "2016-05-04 10:02:45", 
"2016-05-04 10:02:45", "2016-05-04 10:02:45"), stage = c(2L, 
3L, 2L, 3L, 1L, 1L), V7 = c("Detected Organism: Staphylococcus Aureus, Comment: Looks good", 
"Detected Organism: Staphylococcus Aureus, Comment: Looks good", 
"Detected Organism: Staphylococcus Aureus, Comment: Note 1", 
"Detected Organism: Staphylococcus Aureus, Comment: Note 1", 
"Detected Organism: Stenotrophomonas Maltophilia, Comment: new note", 
"Detected Organism: Human Adenovirus 7, Comment: test")), .Names = c("detected_id", 
"reviewer_name", "created_at", "stage", "V7"), row.names = c(NA, 
-6L), class = "data.frame")

SOLUTION：重塑data.frame之前删除detected_id柱，由于使用@eddi

来源

2016-05-06 webDevleoper101

library(data.table) 

setDT(dat)[, paste(V7, collapse = "; ") 
      , by = .(detected_id, reviewer_name, created_at, stage)] 
# detected_id reviewer_name   created_at stage 
#1:   11   mike 2016-05-04 10:02:45  2 
#2:   4   john 2016-05-04 10:02:45  1 
#                               V1 
#1: Detected Organism: Staphylococcus Aureus, Comment: Looks good; Detected Organism: Staphylococcus Aureus, Comment: Note 1 
#2:                  Detected Organism: Human Adenovirus 7, Comment: test

来源

2016-05-06 17:50:21 eddi

良好的解决方案，按预期工作。谢谢！ – webDevleoper101

查看我编辑的 – webDevleoper101

@ webDevleoper101我不确定“失败”对您意味着什么。它完全按预期工作。有一点不清楚你所希望的 - 也许你想从''by'中取出'detected_id'。 – eddi

基础R

with(dat, aggregate(V7,list(detected_id=detected_id, reviewer_name=reviewer_name, created_at=created_at, stage=stage),paste,collapse=' '))

来源

2016-05-06 17:53:02 Ananta

我更喜欢你的解决方案，因为它只是基础R，请检查我刚刚编辑的编辑 – webDevleoper101

如何在R中重塑一个data.frame而没有循环？

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