[R] Convert a column of numbers to a column of strings

[Gabor Grothendieck]

Issue this first:

library(chron)

On Mon, Feb 1, 2010 at 2:42 PM, Gabor Grothendieck
<ggrothendieck at gmail.com> wrote:
> Try this
>
>> Lines <- "Date Time Data
> + 20091209 1200 1
> + 20091209 1500 2
> + 20091209 1800 3
> + 20091210 800 4
> + 20091210 1000 5
> + 20091210 1600 6"
>>
>> toChron <- function(x) as.chron(sprintf("%d %04d", x[,1], x[,2]), "%Y%m%d %H%M")
>>
>> DF <- read.table(textConnection(Lines), header = TRUE)
>> toChron(DF)
> [1] (12/09/09 12:00:00) (12/09/09 15:00:00) (12/09/09 18:00:00)
> (12/10/09 08:00:00) (12/10/09 10:00:00) (12/10/09 16:00:00)
>
> Or if the read problem is to read in a time series try read.zoo in the
> zoo package.  The development version of read.zoo supports
> multi-column indexes:
>
>>
>> library(zoo)
>> # grab development version of read.zoo
>> source("http://r-forge.r-project.org/plugins/scmsvn/viewcvs.php/*checkout*/pkg/zoo/R/read.zoo.R?rev=611&root=zoo")
>> z <- read.zoo(textConnection(Lines), header = TRUE, index = 1:2, FUN = toChron); z
> (12/09/09 12:00:00) (12/09/09 15:00:00) (12/09/09 18:00:00) (12/10/09
> 08:00:00) (12/10/09 10:00:00) (12/10/09 16:00:00)
>                  1                   2                   3
>       4                   5                   6
>
> For more info on dates and times see the article in R News 4/1.  For
> more info on zoo see the 3 vignettes (pdf documents) that come with
> the package.
>
>
> On Mon, Feb 1, 2010 at 1:52 PM, Tam Le <lettam at gmail.com> wrote:
>> Hello,
>>
>> Please excuse me if this question has been asked before. I'm new to R, and
>> have been trying to google the answers without any success.
>>
>> I would like to convert a set of date and time into R date-time class. Right
>> now, the dates and times are in integer format, so I first need to convert
>> them into string, and then to R date-time using strptime. However, I have a
>> problem converting them from integer to string:
>>
>> data:
>>
>> Date Time
>> 20091209 1200
>> 20091209 1500
>> 20091209 1800
>> ....
>> 20091210 800
>> 20091210 1000
>> 20091210 1600
>> ....
>>
>> I used:
>>
>> tempdate=toString(Date)
>> day=substr(tempdate, 7, 8)
>> month=substr(tempdate, 5, 6)
>> year=substr(tempdate, 1, 2)
>> rDate=strptime(paste(year, month, day, sep="-"))
>>
>> the 1st command does not create a new column with string dates in it, it
>> creates a single row that has all the dates in a single string, like this:
>> "20091209, 20091209, .... 20091210, 20091210"
>> "day" ends up being 1 number, 09, instead of a column of days. I ended up
>> having all rDate=2009/12/09, which is the first row.
>>
>> Could you please tell me how to do this correctly?
>>
>> Thanks,
>> Tam
>>
>>
>> --
>>
>>
>> Tam T. Le [MEDS 2001 Sheridan Rd, Evanston IL 60208] [847 708 2439]
>>
>>        [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> 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.
>>
>