[R] median for time data

[Jannis]

I fear nobody can really help you as we can not really understandd what 
your problem is. What does the error message read? What values does 
start.posix have? And what skiers?

You should include the code for a reproducable example. include at least 
2 values for skiers[,3] in their correct format and class, so we can run 
the code ourselves and check what is going on.

Then we can (hopefully) help you.

uvilla schrieb:
> Hi again.
> I´m sorry to ask again but I cannot do the boxplot coprrectly.
> 
> I'm typing:
> 
> start.posix=as.POSIXct(skiers[,3])
> boxplot(start.posix)
> 
> 
> where skiers[,3] is my time data,
> and I get this error
> 
> I have no idea of what that means.. All the other steps are ready, like the
> median of the time data, but Im really stock trying to do the boxplot with
> the time data on the y axis to interprete the median 
> 
> Thanks again
> 
> 
> 
> 
> Jannis v. Buttlar wrote:
>>
>>
>> uvilla schrieb:
>>> When I use strptime() I just get NA NA NA
>>> I`m new at using R, must finisth this work thoug
>>>
>>> I guess Im doing totally wrong, actually everytime i try to use "POSIXct"
>>> it
>>> doesn`t work
>>>
>> If you have a look at help(strptime) you find that you have to specify 
>> the format in which you time is written.
>>
>> Try
>>
>> strptime("08:10:10","%H:%M:%S")
>>
>> The stuff after the comma in the "" is the way to give strptime the
>> format.
>>
>> Now you only have use
>>
>> strptime(vectorwithyourtime,"%H:%M:%S")
>>
>> and you should get a vector with R format times out of it. It uses 
>> todays date though but for your calculations this should work. This 
>> POSIXct format is not very handy to use though, so you perhaps better 
>> consider using library(chron) as Gabor suggested.
>>
>>
>>
>>
>>> Thanks a lot
>>>
>>>
>>>
>>> Jannis wrote:
>>>> Hi,
>>>>
>>>>
>>>> try to convert this to the R time format "POSIXct" or "POSIXlt" via 
>>>> strptime(). Then you can simply substract them. I am not sure whether a 
>>>> median can be calculated though (should be possible as POSIXct stores 
>>>> the value as seconds since 1970....)
>>>>
>>>> Best
>>>> Jannis
>>>>
>>>> uvilla schrieb:
>>>>> Hi everybody
>>>>>
>>>>> How do I do to calculate the median and average of a colum of time data
>>>>> like
>>>>> this: "8:50:10". I also need to plot the time difference between two
>>>>> colums
>>>>> Thanks a lot
>>>> ______________________________________________
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>>>> 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.
>>>>
>>>>
>> ______________________________________________
>> R-help at 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.
>>
>>
> :-((:-((