[R] histogram of time-stamp data

[Rui Barradas]

Hello,

Em 16-07-2012 22:45, e-letter escreveu:
> 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:

No! That instruction is just to create a data example with more 
date/time values, in this case with a total of 1e3 different values. 
What's important is the way to plot the histogram, namely, the cut() 
with two example time periods, and that hist() needs numbers, not cut's 
levels.

Rui Barradas

>
>   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?
>