[R] two different date formats in the same variable

[Gabor Grothendieck]

Try this:

> library(chron)
> x <- c("06/25/04", "06/25/2004", "03/03/59", "03/03/1959")
> chron(x)
[1] 06/25/04 06/25/04 03/03/59 03/03/59


On Mon, Mar 23, 2009 at 8:06 PM, Farrel Buchinsky <fjbuch at gmail.com> wrote:
> How does one convert to a date format when survey respondents have
> used two different date formats whilst entering their data. There were
> clearly told to use mm/dd/yyyy but humans being humans some entered
> mm/dd/yy. There was even validity checks on the forms but I allowed
> them to be overridden since the data is more holy than the format.
>
> The data was downloaded as a csv and read.csv was used to read in.
> There are several date variables (for example date of birth, date of
> diagnosis). Some became character vectors and others become factor
> vectors. Nevertheless I have accomplished most of what I want using
> lines such as
>
> strptime(init.consent$consent.rec,"%m/%d/%Y")
> strptime(x,"%m/%d/%Y")
>  as.Date(x, "%m/%d/%Y")
>
> But what happens when a few of the entries get messed up because they
> are actually formatted %m/%d/%y.
>
> Is there a robust date formatter? Alternatively how would one code
> (presumably using regular expressions) a transforamtion or
> substitution only on the errant entries and thereby turn 06/25/04 into
> 06/25/2004 and 03/03/59 into 03/03/1959?
>
> sessionInfo()
> R version 2.8.1 (2008-12-22)
> i386-pc-mingw32
>
>
> Farrel Buchinsky
>
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