Convert a column of numbers to a column of strings

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]

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