Re: [R] Converting a dataframe column from string to datetime

[raje...@cse.iitm.ac.in]

ok..thanks

----- Original Message -----
From: Don MacQueen <macque...@llnl.gov>
To: raje...@cse.iitm.ac.in, r-help <r-help@r-project.org>
Sent: Fri, 01 Oct 2010 20:51:06 +0530 (IST)
Subject: Re: [R] Converting a dataframe column from string to datetime

You’re working too hard. Use this:



   tms <- as.POSIXct(strptime(v, "%a %b %d %H:%M:%OS %Y"))



Take note of the fact that there are two types of datetime objects:  POSIXct 
and POSIXlt.



Your unlist() gave what seemed a strange result because you used on an “lt” 
object. Had you given it a “ct” object it would have made sense. To see, try


   lapply(v,function(x){as.POSIXct(strptime(x, "%a %b %d %H:%M:%OS %Y"))})



But using lapply() was more complicated than necessary.



-Don



On 9/30/10 10:59 PM, "raje...@cse.iitm.ac.in" <raje...@cse.iitm.ac.in> wrote:





Hi,



I have a dataframe column of the form


v<-c("Fri Feb 05 20:00:01.43000 2010","Fri Feb 05 20:00:02.274000 2010","Fri 
Feb 05 20:00:02.274000 2010","Fri Feb 05 20:00:06.34000 2010")



I need to convert this to datetime form. I did the following..



lapply(v,function(x){strptime(x, "%a %b %d %H:%M:%OS %Y")})



This gives me a list that looks like this...



[[1]]


[1] "2010-02-05 20:00:01.43"


[[2]]


[1] "2010-02-05 20:00:02.274"


[[3]]


[1] "2010-02-05 20:00:02.274"


[[4]]


[1] "2010-02-05 20:00:06.34"



However, when I do an unlist...I gets converted to something like this...



sec  min    hour    mday  mon    year    wday    yday   isdst  sec  min    hour 
   mday  mon    year    wday    yday   isdst  sec 


  1.430   0.000  20.000   5.000   1.000 110.000   5.000  35.000   0.000   2.274 
  0.000  20.000   5.000   1.000 110.000   5.000  35.000   0.000   2.274 


        min    hour    mday  mon    year    wday    yday   isdst  sec  min    
hour    mday  mon    year    wday    yday   isdst  


  0.000  20.000   5.000   1.000 110.000   5.000  35.000   0.000   6.340   0.000 
 20.000   5.000   1.000 110.000   5.000  



I want it to become a dataframe column except for a change in the datatype to 
datetime...how can I achieve this? 


 [[alternative HTML version deleted]]



______________________________________________
R-help@r-project.org mailing list
https://BLOCKEDstat.ethz.ch/mailman/listinfo/r-help


PLEASE do read the posting guide 
http://BLOCKEDwww.BLOCKEDR-project.org/posting-guide.html


and provide commented, minimal, self-contained, reproducible code.


-- 


Don MacQueen


Environmental Protection Department


Lawrence Livermore National Laboratory


925 423-1062





        [[alternative HTML version deleted]]


______________________________________________
R-help@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.