posixct

I have what may be a very simple question. I want to process a column of POSIXct objects from a dataframe and generate a vector of datetime strings. I tried to use the following sapply call dt <- sapply(df$datetime, function(x) format(x,"%Y-%m-%dT%H:%M:%S")) but to no avail. I keep getting the following error: > Error in prettyNum(.Internal(format(x, trim, digits, nsmall, width, 3L, : invalid 'trim' argument When I apply this function to a single POSIXct object from the column, I have no problem. So I'm stumped at the moment about what the problem is. Do I need to do something special with

I have dataset where time.start vary from 5:00:00 to 28:59:59 (i.e. 01.01.2013 28:00:00 is actually 02.01.2013 04:00:00). Dates are in %d.%m.%Y format. Date Time.start 01.01.2013 22:13:07 01.01.2013 22:52:23 01.01.2013 23:34:06 01.01.2013 23:44:25 01.01.2013 27:18:48 01.01.2013 28:41:04 I want to convert it to normal date format. dates$date <- paste(dates$Date,dates$Time.start, sep = " ") dates$date <- as.POSIXct(strptime(dates$date, "%m.%d.%Y %H:%M:%S")) But obviously I have NA for time > 23:59:59 How should I modify my code? E.g. add the time as seconds to the date: df <- read.table(header=T

I am experimenting with R to analyse some measurement data. I have a .csv file containing more than 2 million lines of measurement. Here is an example: 2014-10-22 21:07:03+00:00,7432442.0 2014-10-22 21:07:21+00:00,7432443.0 2014-10-22 21:07:39+00:00,7432444.0 2014-10-22 21:07:57+00:00,7432445.0 2014-10-22 21:08:15+00:00,7432446.0 2014-10-22 21:08:33+00:00,7432447.0 2014-10-22 21:08:52+00:00,7432448.0 2014-10-22 21:09:10+00:00,7432449.0 2014-10-22 21:09:28+00:00,7432450.0 After reading in the file, I want to convert the time to a correct time, using as.POSIXct() . For small files this works

I have a bunch of 1 minute returns in an xts object with the index being POSIXct and time zone being GMT. The returns are on NYSE so I would like to convert to the eastern time zone but I would like to take care of the daylight savings time properly. What is the best way of doing this? I am a bit confused between the EST timezone and the EDT timezone. I would like my times to convert properly to the NY time in winter and summer. Use indexTZ<- and the America/New_York timezone > tail(SPY) SPY.Bid.Price SPY.Ask.Price SPY.Trade.Price SPY.Mid.Price SPY.Volume 2012-08-09 19:54:00 140.47 140.48 140

I am not sure that I can ask this question here, let me know if I should do it somewhere else. I have a data.table with 1e6 rows having this structure: V1 V2 V3 1: 03/09/2011 08:05:40 1145.0 2: 03/09/2011 08:06:01 1207.3 3: 03/09/2011 08:06:17 1198.8 4: 03/09/2011 08:06:20 1158.4 5: 03/09/2011 08:06:40 1112.2 6: 03/09/2011 08:06:59 1199.3 I am converting the V1 and V2 variables to a unique datetime variable, using this code: system.time(DT[,`:=`(index= as.POSIXct(paste(V1,V2), format='%d/%m/%Y %H:%M:%S'), V1=NULL,V2=NULL)]) user system elapsed 47.47 0.16 50.27 Is there any method to improve

I want to make an empty vector of POSIXct so that I can put a POSIXct in it: vec <- vector("POSIXct", 10) vec vec[1] <- "2014-10-27 18:11:36 PDT" vec That does not work. Any ideas? Since there is no POSIX mode , you cannot initialize a POSIXct vector with vector() alone (see ?mode for a list of all mode types). But we can use .POSIXct to create the vector from a character vector. (x <- .POSIXct(character(10))) ## the same as .POSIXct(vector("character", 10)) # [1] NA NA NA NA NA NA NA NA NA NA class(x) # [1] "POSIXct" "POSIXt" Also note that you can also use .POSIXct(integer(10)) for a length