I have been trying to get the year month as a new column to my following example data set.
time site
1 1/01/2000 A
2 1/02/2000 A
3 1/03/2000 A
4 1/04/2000 A
5 1/05/2000 A
6 1/06/2000 A
7 1/07/2000 A
8 1/08/2000 A
9 1/09/2000 A
10 1/10/2000 A
11 1/11/2000 A
12 1/12/2000 A
13 1/01/2001 A
14 1/02/2001 A
15 1/03/2001 A
16 1/04/2001 A
17 1/05/2001 A
18 1/06/2001 A
19 1/07/2001 A
20 1/08/2001 A
21 1/09/2001 A
22 1/10/2001 A
The data set can be accessed using the following dput.
dta<-structure(list(time = structure(c(1L, 3L, 5L, 7L, 9L, 11L, 13L,
15L, 17L, 19L, 21L, 22L, 2L, 4L, 6L, 8L, 10L, 12L, 14L, 16L,
18L, 20L), .Label = c("1/01/2000", "1/01/2001", "1/02/2000",
"1/02/2001", "1/03/2000", "1/03/2001", "1/04/2000", "1/04/2001",
"1/05/2000", "1/05/2001", "1/06/2000", "1/06/2001", "1/07/2000",
"1/07/2001", "1/08/2000", "1/08/2001", "1/09/2000", "1/09/2001",
"1/10/2000", "1/10/2001", "1/11/2000", "1/12/2000"), class = "factor"),
site = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), .Label = "A", class = "factor")), .Names = c("time",
"site"), class = "data.frame", row.names = c(NA, -22L))
I tried with the following codes and returns the same month for all 12.
library(zoo)
dta$y_m = as.yearmon(as.Date(dta$time,"%m/%d/%Y"))
1] "Jan 2000" "Jan 2000" "Jan 2000" "Jan 2000" "Jan 2000" "Jan 2000" "Jan 2000"
[8] "Jan 2000" "Jan 2000" "Jan 2000" "Jan 2000" "Jan 2000" "Jan 2001" "Jan 2001"
[15] "Jan 2001" "Jan 2001" "Jan 2001" "Jan 2001" "Jan 2001" "Jan 2001" "Jan 2001"
[22] "Jan 2001"
Can anybody help me please to get it right. Thank you
Try this:
require(zoo)
as.yearmon(dta$time, format="%d/%m/%Y")
Output:
[1] "Jan 2000" "Feb 2000" "Mar 2000" "Apr 2000" "May 2000" "Jun 2000"
[7] "Jul 2000" "Aug 2000" "Sep 2000" "Oct 2000" "Nov 2000" "Dec 2000"
[13] "Jan 2001" "Feb 2001" "Mar 2001" "Apr 2001" "May 2001" "Jun 2001"
[19] "Jul 2001" "Aug 2001" "Sep 2001" "Oct 2001"