Hi,
Can strptime (or some other function) help me turn the following
column of a data.frame into two new columns, one as date and the other
as time, preserving the AM/PM value?
Thanks,
Mark
> B
ENTRY DATE
1 3/23/2009 6:30:00 AM
2 3/23/2009 6:30:00 AM
3 3/23/2009 6:39:00 AM
4 3/23/2009 6:39:00 AM
5 3/23/2009 6:48:00 AM
6 3/23/2009 6:48:00 AM
7 3/23/2009 7:00:00 AM
> strftime(B, tz="", format="%m/%d/%Y %I:%M:%s %p")
Error in as.POSIXlt.default(x, tz = tz) :
do not know how to convert 'x' to class
"POSIXlt">
> strptime(B, format="%m/%d/%Y %I:%M:%s %p")
[1] NA>
> mode(B)
[1] "list"> class(B)
[1] "data.frame">
Here is one way to do it. Not sure why you want columns with either date or time since you already have them. This will create a POSIXct object you can use for processing and then two character columns with date and time. Exactly what are you going to do with the data.> str(x)'data.frame': 7 obs. of 4 variables: $ V1: int 1 2 3 4 5 6 7 $ V2: chr "3/23/2009" "3/23/2009" "3/23/2009" "3/23/2009" ... $ V3: chr "6:30:00" "6:30:00" "6:39:00" "6:39:00" ... $ V4: chr "AM" "AM" "AM" "AM" ...> y <- x # use temporary so we can try again > y$dateTime <- as.POSIXct(paste(y[[2]], y[[3]], y[[4]]), format="%m/%d/%Y %I:%M:%S %p") > # add columns with only date and time > y$date <- format(y$dateTime, "%m/%d/%Y") > y$time <- format(y$dateTime, "%I:%M:%S %p") > str(y)'data.frame': 7 obs. of 7 variables: $ V1 : int 1 2 3 4 5 6 7 $ V2 : chr "3/23/2009" "3/23/2009" "3/23/2009" "3/23/2009" ... $ V3 : chr "6:30:00" "6:30:00" "6:39:00" "6:39:00" ... $ V4 : chr "AM" "AM" "AM" "AM" ... $ dateTime: POSIXct, format: "2009-03-23 06:30:00" "2009-03-23 06:30:00" "2009-03-23 06:39:00" "2009-03-23 06:39:00" ... $ date : chr "03/23/2009" "03/23/2009" "03/23/2009" "03/23/2009" ... $ time : chr "06:30:00 AM" "06:30:00 AM" "06:39:00 AM" "06:39:00 AM" ...> yV1 V2 V3 V4 dateTime date time 1 1 3/23/2009 6:30:00 AM 2009-03-23 06:30:00 03/23/2009 06:30:00 AM 2 2 3/23/2009 6:30:00 AM 2009-03-23 06:30:00 03/23/2009 06:30:00 AM 3 3 3/23/2009 6:39:00 AM 2009-03-23 06:39:00 03/23/2009 06:39:00 AM 4 4 3/23/2009 6:39:00 AM 2009-03-23 06:39:00 03/23/2009 06:39:00 AM 5 5 3/23/2009 6:48:00 AM 2009-03-23 06:48:00 03/23/2009 06:48:00 AM 6 6 3/23/2009 6:48:00 AM 2009-03-23 06:48:00 03/23/2009 06:48:00 AM 7 7 3/23/2009 7:00:00 AM 2009-03-23 07:00:00 03/23/2009 07:00:00 AM>On Sun, Sep 20, 2009 at 4:11 PM, Mark Knecht <markknecht at gmail.com> wrote:> Hi, > ? ?Can strptime (or some other function) help me turn the following > column of a data.frame into two new columns, one as date and the other > as time, preserving the AM/PM value? > > Thanks, > Mark > >> B > ? ? ? ? ? ? ?ENTRY DATE > 1 ?3/23/2009 6:30:00 AM > 2 ?3/23/2009 6:30:00 AM > 3 ?3/23/2009 6:39:00 AM > 4 ?3/23/2009 6:39:00 AM > 5 ?3/23/2009 6:48:00 AM > 6 ?3/23/2009 6:48:00 AM > 7 ?3/23/2009 7:00:00 AM > >> strftime(B, tz="", format="%m/%d/%Y %I:%M:%s %p") > Error in as.POSIXlt.default(x, tz = tz) : > ?do not know how to convert 'x' to class "POSIXlt" >> > >> strptime(B, format="%m/%d/%Y %I:%M:%s %p") > [1] NA >> > >> mode(B) > [1] "list" >> class(B) > [1] "data.frame" >> > > ______________________________________________ > 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. >-- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem that you are trying to solve?
Note that your explanation refers to strptime but the code uses strftime which accounts for the error. Try this:> Lines <- "ENTRY DATE+ 3/23/2009 6:30:00 AM + 3/23/2009 6:30:00 AM + 3/23/2009 6:39:00 AM + 3/23/2009 6:39:00 AM + 3/23/2009 6:48:00 AM + 3/23/2009 6:48:00 AM + 3/23/2009 7:00:00 AM"> > DF <- read.csv(textConnection(Lines)) > library(chron) > ch <- as.chron(as.character(DF[[1]]), "%m/%d/%Y %I:%M:%S %p") > dd <- dates(ch) > data.frame(Date = dd, Time = times(ch - dd))Date Time 1 03/23/09 06:30:00 2 03/23/09 06:30:00 3 03/23/09 06:39:00 4 03/23/09 06:39:00 5 03/23/09 06:48:00 6 03/23/09 06:48:00 7 03/23/09 07:00:00 Try using dput next time to facilitate copying of your data into readers' sessions.> dput(DF)structure(list(ENTRY.DATE = structure(c(1L, 1L, 2L, 2L, 3L, 3L, 4L), .Label = c("3/23/2009 6:30:00 AM", "3/23/2009 6:39:00 AM", "3/23/2009 6:48:00 AM", "3/23/2009 7:00:00 AM"), class = "factor")), .Names = "ENTRY.DATE", class = "data.frame", row.names = c(NA, -7L)) In the above we used dates and times classes from chron. as.Date(x) will convert an object to Date class if you want that instead. See R News 4/1 for more on dates and times. On Sun, Sep 20, 2009 at 4:11 PM, Mark Knecht <markknecht at gmail.com> wrote:> Hi, > ? ?Can strptime (or some other function) help me turn the following > column of a data.frame into two new columns, one as date and the other > as time, preserving the AM/PM value? > > Thanks, > Mark > >> B > ? ? ? ? ? ? ?ENTRY DATE > 1 ?3/23/2009 6:30:00 AM > 2 ?3/23/2009 6:30:00 AM > 3 ?3/23/2009 6:39:00 AM > 4 ?3/23/2009 6:39:00 AM > 5 ?3/23/2009 6:48:00 AM > 6 ?3/23/2009 6:48:00 AM > 7 ?3/23/2009 7:00:00 AM > >> strftime(B, tz="", format="%m/%d/%Y %I:%M:%s %p") > Error in as.POSIXlt.default(x, tz = tz) : > ?do not know how to convert 'x' to class "POSIXlt" >> > >> strptime(B, format="%m/%d/%Y %I:%M:%s %p") > [1] NA >> > >> mode(B) > [1] "list" >> class(B) > [1] "data.frame" >> > > ______________________________________________ > 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. >