[R] R-help Digest, Vol 113, Issue 19

[e-letter]

On 16/07/2012, r-help-request at r-project.org
<r-help-request at r-project.org> wrote:
> ------------------------------
>
> Message: 77
> Date: Mon, 16 Jul 2012 10:48:39 +0100
> From: Rui Barradas <ruipbarradas at sapo.pt>
> To: e-letter <inpost at gmail.com>
> Cc: r-help at r-project.org
> Subject: Re: [R] histogram of time-stamp data
> Message-ID: <5003E377.3000604 at sapo.pt>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
>
> timestamps <- as.POSIXct(Sys.Date()) + sample(24*60*60, 1e3, TRUE)
>

Why is it necessary to apply the sample to the current date? Looking
at the dataframe, I noticed that values have been changed:

file 'test.txt':
12:19:00
09:30:00
16:56:00
01:56:00
10:44:00
10:31:00
02:14:00
05:05:00
12:52:00
21:50:00

R command terminal input:
> timestamps<-read.table("test.txt")
> timestamps
         V1
1  12:19:00
2  09:30:00
3  16:56:00
4  01:56:00
5  10:44:00
6  10:31:00
7  02:14:00
8  05:05:00
9  12:52:00
10 21:50:00
> timestamps <- as.POSIXct(Sys.Date()) + sample(24*60*60, 1e3, TRUE)
> write.csv(timestamps,file="test1.txt")

test1.txt:
"","x"
"1",2012-07-16 04:52:48
"2",2012-07-16 21:21:28
"3",2012-07-16 18:58:27
"4",2012-07-16 22:17:25
"5",2012-07-16 11:13:52
"6",2012-07-16 03:17:35
"7",2012-07-16 02:14:17
"8",2012-07-16 14:18:27
"9",2012-07-16 14:39:16

Why is this happening?