R help - Aug 2010 - Date and Time Formatting

Hi , 

I have a huge data set (192840 x 5) and would like to convert the date and
time format.

The data looks something like below : 


0	03/01/1983 01:00	-0.10	359.0
0	03/01/1983 02:00	-0.10	359.0
0	03/01/1983 03:00	-0.10	359.0
0	03/01/1983 04:00	-0.10	359.0
0	03/01/1983 05:00	-0.10	359.0
0	03/01/1983 06:00	-0.10	359.0
0	03/01/1983 07:00	-0.10	359.0

I will like to change the date format to 1983-01-03 and the time format to
01:00:00.

I have used the following code : 

sample <- read.table("321.txt",header=F)
Date = sample[,2]
Time = sample[,3]
timedf <- data.frame(Date, Time) 
strptime( with(timedf, paste(Date,Time) ), format="%d/%m/%y %H:%M")

The code works when I define Date and Time individually*, but when I try to
run it with all the data in the datasets the solution that comes out is
"NA".

Is there a way around this?

Your help is very much appreciated

*E.g
timedf <- data.frame(Date1 = "20/12/08", Time1= "17:00")
> strptime( with(timedf, paste(Date1,Time1) ), format="%d/%m/%y
%H:%M")
[] 2008-12-20 17:00:00


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Hi

r-help-bounces at r-project.org napsal dne 02.08.2010 10:21:25:
> 
> Hi , 
> 
> I have a huge data set (192840 x 5) and would like to convert the date 
and
> time format.
> 
> The data looks something like below : 
> 
> 
> 0   03/01/1983 01:00   -0.10   359.0
> 0   03/01/1983 02:00   -0.10   359.0
> 0   03/01/1983 03:00   -0.10   359.0
> 0   03/01/1983 04:00   -0.10   359.0
> 0   03/01/1983 05:00   -0.10   359.0
> 0   03/01/1983 06:00   -0.10   359.0
> 0   03/01/1983 07:00   -0.10   359.0
> 
> I will like to change the date format to 1983-01-03 and the time format 
to
> 01:00:00.
> 
> I have used the following code : 
> 
> sample <- read.table("321.txt",header=F)
> Date = sample[,2]
> Time = sample[,3]
> timedf <- data.frame(Date, Time) 
> strptime( with(timedf, paste(Date,Time) ), format="%d/%m/%y
%H:%M")
> 
> The code works when I define Date and Time individually*, but when I try 
to
> run it with all the data in the datasets the solution that comes out is
> "NA".
The code should not work, at least with the data snippet you stated above.

strptime( with(timedf, paste(Date,Time) ), format="%d/%m/%Y %H:%M")

shall work, although I do not know if your date values are consistent 
throughout whole data frame.

see ?strptime and look to Details section

Regards
Petr
> 
> Is there a way around this?
> 
> Your help is very much appreciated
> 
> *E.g
> timedf <- data.frame(Date1 = "20/12/08", Time1=
"17:00")
> > strptime( with(timedf, paste(Date1,Time1) ), format="%d/%m/%y
%H:%M")
> [] 2008-12-20 17:00:00
> 
> 
> -- 
> View this message in context: 
http://r.789695.n4.nabble.com/Date-and-Time-
> Formatting-tp2310015p2310015.html
> Sent from the R help mailing list archive at Nabble.com.
> 
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