如何在R中将日期或日期向量转换为POSIXct？
要将日期或日期向量转换为POSIXct，我们可以使用as.POSIXct函数，但我们还需要在函数内部传递适当的日期格式。例如，如果我们有一个日期“2020-11-14”，则可以使用as.POSIXct（“2020-11-14”，format=“％Y-％m-％d”）将其转换为POSIXct。
例1
> date1<-"2020-04-01" > as.POSIXct(date1,format="%Y-%m-%d")
输出结果
[1] "2020-04-01 IST"
例2
> date2<-sample(c("2020-04-01","2020-10-01","2020-02-12","2020-04-11","2020-01-21","2020-04-27","2020-03-31","2020-05-01","2020-05-11","2020-06-01"),60,replace=TRUE)
> date2输出结果
[1] "2020-02-12" "2020-06-01" "2020-04-01" "2020-05-01" "2020-01-21" [6] "2020-01-21" "2020-06-01" "2020-04-27" "2020-05-11" "2020-06-01" [11] "2020-01-21" "2020-03-31" "2020-05-01" "2020-02-12" "2020-01-21" [16] "2020-05-01" "2020-03-31" "2020-04-01" "2020-05-01" "2020-01-21" [21] "2020-05-01" "2020-04-11" "2020-05-11" "2020-04-01" "2020-03-31" [26] "2020-04-11" "2020-04-01" "2020-03-31" "2020-04-01" "2020-04-11" [31] "2020-05-11" "2020-06-01" "2020-03-31" "2020-04-27" "2020-01-21" [36] "2020-01-21" "2020-04-01" "2020-06-01" "2020-05-01" "2020-10-01" [41] "2020-04-27" "2020-01-21" "2020-10-01" "2020-01-21" "2020-04-01" [46] "2020-04-11" "2020-10-01" "2020-10-01" "2020-05-11" "2020-02-12" [51] "2020-05-01" "2020-05-01" "2020-01-21" "2020-01-21" "2020-02-12" [56] "2020-05-01" "2020-02-12" "2020-02-12" "2020-04-11" "2020-10-01"
示例
> as.POSIXct(date2,format="%Y-%m-%d")
输出结果
[1] "2020-02-12 IST" "2020-06-01 IST" "2020-04-01 IST" "2020-05-01 IST" [5] "2020-01-21 IST" "2020-01-21 IST" "2020-06-01 IST" "2020-04-27 IST" [9] "2020-05-11 IST" "2020-06-01 IST" "2020-01-21 IST" "2020-03-31 IST" [13] "2020-05-01 IST" "2020-02-12 IST" "2020-01-21 IST" "2020-05-01 IST" [17] "2020-03-31 IST" "2020-04-01 IST" "2020-05-01 IST" "2020-01-21 IST" [21] "2020-05-01 IST" "2020-04-11 IST" "2020-05-11 IST" "2020-04-01 IST" [25] "2020-03-31 IST" "2020-04-11 IST" "2020-04-01 IST" "2020-03-31 IST" [29] "2020-04-01 IST" "2020-04-11 IST" "2020-05-11 IST" "2020-06-01 IST" [33] "2020-03-31 IST" "2020-04-27 IST" "2020-01-21 IST" "2020-01-21 IST" [37] "2020-04-01 IST" "2020-06-01 IST" "2020-05-01 IST" "2020-10-01 IST" [41] "2020-04-27 IST" "2020-01-21 IST" "2020-10-01 IST" "2020-01-21 IST" [45] "2020-04-01 IST" "2020-04-11 IST" "2020-10-01 IST" "2020-10-01 IST" [49] "2020-05-11 IST" "2020-02-12 IST" "2020-05-01 IST" "2020-05-01 IST" [53] "2020-01-21 IST" "2020-01-21 IST" "2020-02-12 IST" "2020-05-01 IST" [57] "2020-02-12 IST" "2020-02-12 IST" "2020-04-11 IST" "2020-10-01 IST"
例子3
> date3<-rep(c("2020-04-01","2020-10-01","2020-02-12","2020-04-11","2020-01-21","2020-04-27","2020-03-31","2020-05-01","2020-05-11","2020-06-01"),10)
> date3输出结果
[1] "2020-04-01" "2020-10-01" "2020-02-12" "2020-04-11" "2020-01-21" [6] "2020-04-27" "2020-03-31" "2020-05-01" "2020-05-11" "2020-06-01" [11] "2020-04-01" "2020-10-01" "2020-02-12" "2020-04-11" "2020-01-21" [16] "2020-04-27" "2020-03-31" "2020-05-01" "2020-05-11" "2020-06-01" [21] "2020-04-01" "2020-10-01" "2020-02-12" "2020-04-11" "2020-01-21" [26] "2020-04-27" "2020-03-31" "2020-05-01" "2020-05-11" "2020-06-01" [31] "2020-04-01" "2020-10-01" "2020-02-12" "2020-04-11" "2020-01-21" [36] "2020-04-27" "2020-03-31" "2020-05-01" "2020-05-11" "2020-06-01" [41] "2020-04-01" "2020-10-01" "2020-02-12" "2020-04-11" "2020-01-21" [46] "2020-04-27" "2020-03-31" "2020-05-01" "2020-05-11" "2020-06-01" [51] "2020-04-01" "2020-10-01" "2020-02-12" "2020-04-11" "2020-01-21" [56] "2020-04-27" "2020-03-31" "2020-05-01" "2020-05-11" "2020-06-01" [61] "2020-04-01" "2020-10-01" "2020-02-12" "2020-04-11" "2020-01-21" [66] "2020-04-27" "2020-03-31" "2020-05-01" "2020-05-11" "2020-06-01" [71] "2020-04-01" "2020-10-01" "2020-02-12" "2020-04-11" "2020-01-21" [76] "2020-04-27" "2020-03-31" "2020-05-01" "2020-05-11" "2020-06-01" [81] "2020-04-01" "2020-10-01" "2020-02-12" "2020-04-11" "2020-01-21" [86] "2020-04-27" "2020-03-31" "2020-05-01" "2020-05-11" "2020-06-01" [91] "2020-04-01" "2020-10-01" "2020-02-12" "2020-04-11" "2020-01-21" [96] "2020-04-27" "2020-03-31" "2020-05-01" "2020-05-11" "2020-06-01"
示例
> as.POSIXct(date3,format="%Y-%m-%d")
输出结果
[1] "2020-04-01 IST" "2020-10-01 IST" "2020-02-12 IST" "2020-04-11 IST" [5] "2020-01-21 IST" "2020-04-27 IST" "2020-03-31 IST" "2020-05-01 IST" [9] "2020-05-11 IST" "2020-06-01 IST" "2020-04-01 IST" "2020-10-01 IST" [13] "2020-02-12 IST" "2020-04-11 IST" "2020-01-21 IST" "2020-04-27 IST" [17] "2020-03-31 IST" "2020-05-01 IST" "2020-05-11 IST" "2020-06-01 IST" [21] "2020-04-01 IST" "2020-10-01 IST" "2020-02-12 IST" "2020-04-11 IST" [25] "2020-01-21 IST" "2020-04-27 IST" "2020-03-31 IST" "2020-05-01 IST" [29] "2020-05-11 IST" "2020-06-01 IST" "2020-04-01 IST" "2020-10-01 IST" [33] "2020-02-12 IST" "2020-04-11 IST" "2020-01-21 IST" "2020-04-27 IST" [37] "2020-03-31 IST" "2020-05-01 IST" "2020-05-11 IST" "2020-06-01 IST" [41] "2020-04-01 IST" "2020-10-01 IST" "2020-02-12 IST" "2020-04-11 IST" [45] "2020-01-21 IST" "2020-04-27 IST" "2020-03-31 IST" "2020-05-01 IST" [49] "2020-05-11 IST" "2020-06-01 IST" "2020-04-01 IST" "2020-10-01 IST" [53] "2020-02-12 IST" "2020-04-11 IST" "2020-01-21 IST" "2020-04-27 IST" [57] "2020-03-31 IST" "2020-05-01 IST" "2020-05-11 IST" "2020-06-01 IST" [61] "2020-04-01 IST" "2020-10-01 IST" "2020-02-12 IST" "2020-04-11 IST" [65] "2020-01-21 IST" "2020-04-27 IST" "2020-03-31 IST" "2020-05-01 IST" [69] "2020-05-11 IST" "2020-06-01 IST" "2020-04-01 IST" "2020-10-01 IST" [73] "2020-02-12 IST" "2020-04-11 IST" "2020-01-21 IST" "2020-04-27 IST" [77] "2020-03-31 IST" "2020-05-01 IST" "2020-05-11 IST" "2020-06-01 IST" [81] "2020-04-01 IST" "2020-10-01 IST" "2020-02-12 IST" "2020-04-11 IST" [85] "2020-01-21 IST" "2020-04-27 IST" "2020-03-31 IST" "2020-05-01 IST" [89] "2020-05-11 IST" "2020-06-01 IST" "2020-04-01 IST" "2020-10-01 IST" [93] "2020-02-12 IST" "2020-04-11 IST" "2020-01-21 IST" "2020-04-27 IST" [97] "2020-03-31 IST" "2020-05-01 IST" "2020-05-11 IST" "2020-06-01 IST"