[R] histogram of time-stamp data
Rui Barradas
ruipbarradas at sapo.pt
Tue Jul 17 10:37:28 CEST 2012
Hello,
That's not the error I've had. You must be aware that read.table creates
a data.frame and therefore the object 'timestamps' is NOT holding time
stamps, it's holding a vector, 'V1', of time stamps.
timestamps <- read.table(text="
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
", stringsAsFactors=FALSE)
str(timestamps)
timestamps <- as.POSIXct(timestamps$V1, format="%H:%M:%S") # here
h1 <- cut(timestamps, breaks="hour")
h2 <- cut(timestamps, breaks="15 mins")
op <- par(mfrow=c(1, 2))
hist(as.integer(h1))
hist(as.integer(h2))
par(op)
And the rest works.
Rui Barradas
Em 17-07-2012 07:11, e-letter escreveu:
> On 16/07/2012, Rui Barradas <ruipbarradas at sapo.pt> wrote:
>> 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.
>>
>
> With the original data provided, R reports an error, that "'x' must be numeric'.
>
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