R 基于分组的第二个数据帧,在一个数据帧中创建日期序列
我有两个数据帧共享一个分组ID。我想根据另一个设置的条件在其中创建一个日期序列。MRE如下所示:R 基于分组的第二个数据帧,在一个数据帧中创建日期序列,r,data.table,R,Data.table,我有两个数据帧共享一个分组ID。我想根据另一个设置的条件在其中创建一个日期序列。MRE如下所示: jdates <- structure(list(Group.1 = c(8, 9), x = structure(c(16674, 16661), class = "Date")), .Names = c("Group.1", "x"), row.names = c(NA, -2L), class = c("data.table", "data.frame")) jtrying <-
jdates <- structure(list(Group.1 = c(8, 9), x = structure(c(16674, 16661), class = "Date")), .Names = c("Group.1", "x"), row.names = c(NA, -2L), class = c("data.table", "data.frame"))
jtrying <- structure(list(id = c(8, 8, 8, 9, 9, 9), values1 = 1:6, values2 = 7:12), .Names = c("id", "values1", "values2"), row.names = c(NA, -6L), class = c("data.table", "data.frame"))
我一直在尝试data.table方法,因为它们被认为更快(而且实际数据相当大),但实际上,任何(合理的)方法都可以
我的预期结果是data.frame,如下所示:
jtrying
id values1 values2 date
1: 8 1 7 2015-08-28
2: 8 2 8 2015-08-29
3: 8 3 9 2015-08-30
4: 9 4 10 2015-08-15
5: 9 5 11 2015-08-16
6: 9 6 12 2015-08-17
这是我要做的
jtrying[jdates,
date := seq(from=x+1, by=1, length.out=.N)
, on=c(id="Group.1"), by=.EACHI]
这种语法X[Y,newcol:=…,on=c(Xcol=Ycol),by=.EACHI]
的工作原理如下:
jdates <- structure(list(Group.1 = c(8, 9), x = structure(c(16674, 16661), class = "Date")), .Names = c("Group.1", "x"), row.names = c(NA, -2L), class = c("data.table", "data.frame"))
jtrying <- structure(list(id = c(8, 8, 8, 9, 9, 9), values1 = 1:6, values2 = 7:12), .Names = c("id", "values1", "values2"), row.names = c(NA, -6L), class = c("data.table", "data.frame"))
在上的X
中标识的列上与
合并Y
分别为合并列的每个值构建其X
(即,newcol
)by=.EACHI