I'm sure this is just the result of a basic misunderstanding of the
syntax of R, but I am stumped.
A <-
read.table(file="sumByThirtyMinute.csv",sep=",",col.names=c("date","pandl"))
A now consists of thousands of rows, but A$date is a string...
...
3183 2006-02-28 12:00:00 548.470
3184 2006-02-28 12:30:00 515.240
3185 2006-02-28 13:00:00 140.120
3186 2006-02-28 13:30:00 450.940
3187 2006-02-28 14:00:00 318.570
...
So, I try to convert A$date to a POSIXlt ...
A[,1]<-strptime(A$date,"%Y-%m-%d %H:%M:%s")
A$date<-strptime(A$date,"%Y-%m-%d %H:%M:%s")
which gives me a warning that the length of the array I am trying to
replace A$date with is 9 ... but if I print strptime(A$date,"%Y-%m-%d
%H:%M:%s"), it clearly has thousands of rows. Yet, if I ask for
length(strptime(A$date,"%Y-%m-%d %H:%M:%s")), I get 9.
What am I doing wrong? Do I need to convert the return value of
strptime(A$date,"%Y-%m-%d %H:%M:%s") to some array/vector/matrix
datatype before attempting to assign it?
Thanks,
Andrew
maybe you need to transform A$date to character: A$date <- strptime(as.character(A$date), ...) see also: ?ISOdatetime Andrew Athan a ?crit :>I'm sure this is just the result of a basic misunderstanding of the >syntax of R, but I am stumped. > >A <- >read.table(file="sumByThirtyMinute.csv",sep=",",col.names=c("date","pandl")) > >A now consists of thousands of rows, but A$date is a string... >... >3183 2006-02-28 12:00:00 548.470 >3184 2006-02-28 12:30:00 515.240 >3185 2006-02-28 13:00:00 140.120 >3186 2006-02-28 13:30:00 450.940 >3187 2006-02-28 14:00:00 318.570 >... > > > > >So, I try to convert A$date to a POSIXlt ... > >A[,1]<-strptime(A$date,"%Y-%m-%d %H:%M:%s") >A$date<-strptime(A$date,"%Y-%m-%d %H:%M:%s") > > >which gives me a warning that the length of the array I am trying to >replace A$date with is 9 ... but if I print strptime(A$date,"%Y-%m-%d >%H:%M:%s"), it clearly has thousands of rows. Yet, if I ask for >length(strptime(A$date,"%Y-%m-%d %H:%M:%s")), I get 9. > >What am I doing wrong? Do I need to convert the return value of >strptime(A$date,"%Y-%m-%d %H:%M:%s") to some array/vector/matrix >datatype before attempting to assign it? > >Thanks, >Andrew > >______________________________________________ >R-help at stat.math.ethz.ch mailing list >https://stat.ethz.ch/mailman/listinfo/r-help >PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > > >
POSIXct, not POSIXlt, are used in data frame columns. See ?POSIXct where this is mentioned and try: A$date <- as.POSIXct(A$date) Also be sure to read R News 4/1 for more about dates and times. On 3/6/06, Andrew Athan <aathan_R_1542 at memeplex.com> wrote:> > I'm sure this is just the result of a basic misunderstanding of the > syntax of R, but I am stumped. > > A <- > read.table(file="sumByThirtyMinute.csv",sep=",",col.names=c("date","pandl")) > > A now consists of thousands of rows, but A$date is a string... > ... > 3183 2006-02-28 12:00:00 548.470 > 3184 2006-02-28 12:30:00 515.240 > 3185 2006-02-28 13:00:00 140.120 > 3186 2006-02-28 13:30:00 450.940 > 3187 2006-02-28 14:00:00 318.570 > ... > > > > > So, I try to convert A$date to a POSIXlt ... > > A[,1]<-strptime(A$date,"%Y-%m-%d %H:%M:%s") > A$date<-strptime(A$date,"%Y-%m-%d %H:%M:%s") > > > which gives me a warning that the length of the array I am trying to > replace A$date with is 9 ... but if I print strptime(A$date,"%Y-%m-%d > %H:%M:%s"), it clearly has thousands of rows. Yet, if I ask for > length(strptime(A$date,"%Y-%m-%d %H:%M:%s")), I get 9. > > What am I doing wrong? Do I need to convert the return value of > strptime(A$date,"%Y-%m-%d %H:%M:%s") to some array/vector/matrix > datatype before attempting to assign it? > > Thanks, > Andrew > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html >
Try prepending as.POSIXct A[,1] <- as.POSIXct(strptime(A$date,"%Y-%m-%d %H:%M:%s")) A. On Mon, Mar 06, 2006 at 11:58:01PM -0500, Andrew Athan wrote:> > I'm sure this is just the result of a basic misunderstanding of the > syntax of R, but I am stumped. > > A <- > read.table(file="sumByThirtyMinute.csv",sep=",",col.names=c("date","pandl")) > > A now consists of thousands of rows, but A$date is a string... > ... > 3183 2006-02-28 12:00:00 548.470 > 3184 2006-02-28 12:30:00 515.240 > 3185 2006-02-28 13:00:00 140.120 > 3186 2006-02-28 13:30:00 450.940 > 3187 2006-02-28 14:00:00 318.570 > ... > > > > > So, I try to convert A$date to a POSIXlt ... > > A[,1]<-strptime(A$date,"%Y-%m-%d %H:%M:%s") > A$date<-strptime(A$date,"%Y-%m-%d %H:%M:%s") > > > which gives me a warning that the length of the array I am trying to > replace A$date with is 9 ... but if I print strptime(A$date,"%Y-%m-%d > %H:%M:%s"), it clearly has thousands of rows. Yet, if I ask for > length(strptime(A$date,"%Y-%m-%d %H:%M:%s")), I get 9. > > What am I doing wrong? Do I need to convert the return value of > strptime(A$date,"%Y-%m-%d %H:%M:%s") to some array/vector/matrix > datatype before attempting to assign it? > > Thanks, > Andrew > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html-- Andrew Robinson Department of Mathematics and Statistics Tel: +61-3-8344-9763 University of Melbourne, VIC 3010 Australia Fax: +61-3-8344-4599 Email: a.robinson at ms.unimelb.edu.au http://www.ms.unimelb.edu.au