[英]Extracting most recent date from rows in a data frame
我正在使用一個具有多個相互關聯的日期的數據框,但最重要的是我需要提取最新日期。 我在這里看到了示例,但沒有找到我想要的東西。 因此,我的示例數據幀如下:
ID date1 date2 date3
1 01/12/15 02/04/07 07/06/16
2 03/29/12 02/16/16 09/01/10
3 12/01/15 07/07/07 11/13/12
但是我想要得到的輸出可以給我:
ID date1 date2 date3 max
1 01/12/15 02/04/07 07/06/16 07/06/16
2 03/29/12 02/16/16 09/01/10 02/16/16
3 12/01/15 07/07/07 11/13/12 12/01/15
我看到人們使用plyr和dplyr,但是我對那些軟件包不熟悉。 任何幫助表示贊賞!
編輯:我能夠運行@akrun給出的內容,但是遇到了空字段日期的問題。 我提供了一個示例,如下所示:
ID date1 date2 date3
1 01/12/15 NA 07/06/16
2 NA 02/16/16 09/01/10
3 12/01/15 07/07/07 NA
因此,對於那些空白點,我仍然希望按以下方式轉換數據幀:
ID date1 date2 date3 max
1 01/12/15 NA 07/06/16 07/06/16
2 NA 02/16/16 09/01/10 02/16/16
3 12/01/15 07/07/07 NA 12/01/15
我們可以轉換為Date
類,然后使用max.col
獲取列索引,與行索引cbind
,從'df1'中提取元素並創建'max'列。
df1$max <- df1[cbind(1:nrow(df1), max.col(sapply(df1[-1], as.Date, format = "%m/%d/%y"))+1)]
df1
# ID date1 date2 date3 max
#1 1 01/12/15 02/04/07 07/06/16 07/06/16
#2 2 03/29/12 02/16/16 09/01/10 02/16/16
#3 3 12/01/15 07/07/07 11/13/12 12/01/15
或者另一種選擇是apply
與MARGIN = 1
df1$max <- apply(df1[-1], 1, function(x) x[which.max(as.Date(x, "%m/%d/%y"))])
df1 <- structure(list(ID = 1:3, date1 = c("01/12/15", "03/29/12", "12/01/15"
), date2 = c("02/04/07", "02/16/16", "07/07/07"), date3 = c("07/06/16",
"09/01/10", "11/13/12")), .Names = c("ID", "date1", "date2",
"date3"), class = "data.frame", row.names = c("1", "2", "3"))
轉換為Date
對象后使用pmax
:
dat[-1] <- lapply(dat[-1], as.Date, format="%m/%d/%y")
dat$max <- do.call(pmax, dat[-1])
# ID date1 date2 date3 max
#1 1 2015-01-12 2007-02-04 2016-07-06 2016-07-06
#2 2 2012-03-29 2016-02-16 2010-09-01 2016-02-16
#3 3 2015-12-01 2007-07-07 2012-11-13 2015-12-01
將dat
用作:
dat <- structure(list(ID = 1:3, date1 = structure(1:3, .Label = c("01/12/15",
"03/29/12", "12/01/15"), class = "factor"), date2 = structure(1:3, .Label = c("02/04/07",
"02/16/16", "07/07/07"), class = "factor"), date3 = structure(1:3, .Label = c("07/06/16",
"09/01/10", "11/13/12"), class = "factor")), .Names = c("ID",
"date1", "date2", "date3"), class = "data.frame", row.names = c("1",
"2", "3"))
如果您對使用SQL感到更自在,則sqldf
庫為您提供了獲取最后日期的另一種方法:
data1<-data.frame(id=c("1","2","3"),
date1=as.Date(c("01/12/15","03/29/12","12/01/15"),"%m/%d/%y"),
date2=as.Date(c("02/04/07","02/16/16","07/07/07"),"%m/%d/%y"),
date3=as.Date(c("07/06/16","09/01/10","11/13/12"),"%m/%d/%y"))
library(sqldf)
data2 = sqldf("SELECT id,
max(date1,date2,date3) as 'max__Date'
FROM data1", method = "name__class")
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