Thanks again!

On Thu, Dec 3, 2009 at 2:19 PM, David Winsemius <dwinsemius@comcast.net>wrote:

>
>  On Dec 3, 2009, at 2:14 PM, Peng Cai wrote:
>
> Also, can I control for number of decimal places printed. Like when I use
> "mean" function. By default it shows upto 7 dec. Thanks!
>
>
> > print(4.567891234, digits=3)
> [1] 4.57
>
>
>
>
> On Thu, Dec 3, 2009 at 2:08 PM, Peng Cai <pengcaimaillist@gmail.com>wrote:
>
>> Thanks David for your suggestions.
>>
>>
>> On Thu, Dec 3, 2009 at 2:03 PM, David Winsemius <dwinsemius@comcast.net>wrote:
>>
>>>
>>> On Dec 3, 2009, at 1:50 PM, Peng Cai wrote:
>>>
>>> Hi R Users,
>>>>
>>>> I'm wondering how can I calculate two (or three) way sum of a variable.
>>>> A
>>>> sample data is:
>>>>
>>>> State Month Year Value
>>>> NC Jan 1996 1
>>>> NC Jan 1996 2
>>>> NC Feb 1997 2
>>>> NC Feb 1997 3
>>>> NC Mar 1998 3
>>>> NC Mar 1998 4
>>>> NY Jan 1996 4
>>>> NY Jan 1996 5
>>>> NY Feb 1997 5
>>>> NY Feb 1997 6
>>>> NY Mar 1998 6
>>>> NY Mar 1998 7
>>>>
>>>> I'm trying to sum up "value" column by State*Month and by
>>>> State*Month*Year.
>>>>
>>>
>>> ?tapply
>>>
>>> as in
>>>
>>> sum.tbl <- with(dftbl, tapply(Value, list(State, Month), sum) )
>>>
>>>
>>> Also, I may need to calculate mean value along with "sum".
>>>>
>>>
>>> Use the mean function in the above formulation to get means, length to
>>> get counts, or perhaps summary .... or one of the several packages that
>>> offer a "describe" function. So many functions, so little time.
>>>
>>> -- David
>>>
>>>
>>>
>>>> Any help would be greatly appreciated,
>>>>
>>>> Thanks,
>>>> Peng
>>>>
>>>>        [[alternative HTML version deleted]]
>>>>
>>>> ______________________________________________
>>>> R-help@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<http://www.r-project.org/posting-guide.html>
>>>> and provide commented, minimal, self-contained, reproducible code.
>>>>
>>>
>>> David Winsemius, MD
>>> Heritage Laboratories
>>> West Hartford, CT
>>>
>>>
>>
>
>  David Winsemius, MD
> Heritage Laboratories
> West Hartford, CT
>
>

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