[R] convert 'character' vector containing mixed formats to 'Date'

Thu Jun 21 22:43:39 CEST 2012

HI,
#Instead of
x1[is.na(x1)]<-c(x2[8],x2[10])
#You can use more general form,
x1[is.na(x1)]<-x2[!is.na(x2)]
x1
 [1] "2005-03-01" "2004-04-13" "2005-05-02" "2005-05-02" "2007-05-07"
 [6] "2004-04-22" "2005-04-21" "2008-04-30" "2003-05-13" "2008-05-29"
[11] "1999-05-19" "2000-05-17" "2000-05-17"

A.K.

----- Original Message -----
From: arun <smartpink111 at yahoo.com>
To: Liviu Andronic <landronimirc at gmail.com>
Cc: R help <r-help at r-project.org>
Sent: Thursday, June 21, 2012 1:10 PM
Subject: Re: [R] convert 'character' vector containing mixed formats to 'Date'

HI,

You could also try it with strptime to get the result:

x <- c("1/3/2005", "13/04/2004", "2/5/2005", "2/5/2005", "7/5/2007",
      "22/04/2004", "21/04/2005", "20080430", "13/05/2003", "20080529",
      NA, NA, "19/05/1999", "17/05/2000", "17/05/2000")
 x<-as.character(na.omit(x))
x1<-strptime(x,"%d/%m/%Y")
x2<-strptime(x,"%Y%m%d")
x1[is.na(x1)]<-c(x2[8],x2[10])
 x1
 [1] "2005-03-01" "2004-04-13" "2005-05-02" "2005-05-02" "2007-05-07"
 [6] "2004-04-22" "2005-04-21" "2008-04-30" "2003-05-13" "2008-05-29"
[11] "1999-05-19" "2000-05-17" "2000-05-17"

A.K.

----- Original Message -----
From: Liviu Andronic <landronimirc at gmail.com>
To: "r-help at r-project.org Help" <r-help at r-project.org>
Cc: 
Sent: Thursday, June 21, 2012 8:48 AM
Subject: [R] convert 'character' vector containing mixed formats to 'Date'

Dear all
I have a 'character' vector containing mixed formats (thanks Excel!)
and I'd like to translate it into a default "%Y-%m-%d" Date vector.
x <- c("1/3/2005", "13/04/2004", "2/5/2005", "2/5/2005", "7/5/2007",
       "22/04/2004", "21/04/2005", "20080430", "13/05/2003", "20080529",
       NA, NA, "19/05/1999", "17/05/2000", "17/05/2000")

In the above you will see that some dates are of format="%d/%m/%Y",
others of format="%Y%m%d" and some NA values. Can you suggest a
straight-forward way of transforming these to a uniform 'character' or
'Date' vector? I tried to do the following, but it outputs very
strange results:
> x
[1] "1/3/2005"   "13/04/2004" "2/5/2005"   "2/5/2005"   "7/5/2007"
"22/04/2004"
[7] "21/04/2005" "20080430"   "13/05/2003" "20080529"   NA
NA
[13] "19/05/1999" "17/05/2000" "17/05/2000"
> sum(xa <- grepl('/', x))
[1] 11
> sum(xb  <- grepl('200', substr(x, 1,4)))
[1] 2
> sum(xc <- is.na(x))
[1] 2
> x[xa] <- as.Date(x[xa], format="%d/%m/%Y")
> x[xb] <- as.Date(x[xb], format="%Y%m%d")
> x
[1] "12843" "12521" "12905" "12905" "13640" "12530" "12894" "13999"
"12185" "14028"
[11] NA      NA      "10730" "11094" "11094"

The culprit is likely that the 'x' vector is 'character' throughout,
but I'm not sure how to work around. For example, I couldn't figure
how to create an empty 'Date' vector. Regards
Liviu

-- 
Do you know how to read?
http://www.alienetworks.com/srtest.cfm
http://goodies.xfce.org/projects/applications/xfce4-dict#speed-reader
Do you know how to write?
http://garbl.home.comcast.net/~garbl/stylemanual/e.htm#e-mail

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.