[R] Extract month and year as one column

[David Winsemius]

On Mar 13, 2015, at 8:36 AM, Kumsaa wrote:

> How could I extract both month and year from a date? I know how to
> separately extract both using lubridate package:
> 
> df$month <- month(df$date)
> df$year<- year(df$date)

Use format.Date:  # and see ?strptime for more format specifications.

> format(mydf$date, format="%Y %b")
 [1] "2011 Jan" "2011 Jan" "2011 Jan" "2011 Jan" "2011 Jan" "2011 Jan"
 [7] "2011 Jan" "2011 Jan" "2011 Jan" "2011 Jan" "2011 Jan" "2011 Jan"
[13] "2011 Jan" "2011 Jan" "2011 Jan" "2012 Jan" "2012 Jan" "2012 Jan"
[19] "2012 Jan" "2012 Jan" "2012 Jan" "2012 Jan" "2012 Jan" "2012 Jan"
[25] "2012 Jan" "2012 Jan" "2012 Jan" "2012 Jan" "2012 Jan" "2012 Jan"
> 
> I wish to extract year and month as one column
> 
>> dput(mydf)
> structure(list(date = structure(c(14975, 14976, 14977, 14978,
> 14979, 14980, 14981, 14982, 14983, 14984, 14985, 14986, 14987,
> 14988, 14989, 15340, 15341, 15342, 15343, 15344, 15345, 15346,
> 15347, 15348, 15349, 15350, 15351, 15352, 15353, 15354), class = "Date"),
>    temp = c(6.5140544091004, 3.69073712745884, 3.04839429519466,
>    9.16988228171461, -1.17176248610603, 2.88216040747883,
> 4.98853844809017,
>    4.07520306701834, 9.82902813943658, 2.79305715971987, 8.04721677924611,
>    7.50667729759095, 2.91055000121842, 1.65559895014064, 4.8019596483372,
>    16.2567986804179, 13.3352908067145, 16.6955807821108, 6.28373374879922,
>    6.97181051627531, 5.74282686202818, 4.37018386569785, 12.5725962512824,
>    4.6583055309578, 8.76457542037641, 10.7070862034423, 12.84023567151,
>    5.78620621848167, 5.98643374478599, 13.0993210289842)), .Names =
> c("date",
> "temp"), row.names = c(NA, 30L), class = "data.frame")
> 
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> 
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David Winsemius
Alameda, CA, USA