[R] aggregate function

[Michel Schnitz]

it works. thanks a lot.

Gabor Grothendieck wrote:
> try this.  The first group of lines recreates your data frame, DF, and
> the last line is the aggregate:
> 
> 
> Input <- "Date            Time    z
> 2006-01-01      21:00   6,2
> 2006-01-01      22:00   5,7
> 2006-01-01      23:00   3,2
> 2006-01-02      00:00   7,8
> 2006-01-02      01:00   6,8
> 2006-01-02      02:00   5,6
> 2007-03-30      22:00   5,2
> 2007-03-30      23:00   8,3
> 2007-03-31      00:00   6,4
> 2007-03-31      01:00   7,4
> "
> DF <- read.table(textConnection(Input), header = TRUE, as.is = TRUE)
> DF$z <- as.numeric(sub(",", ".", DF$z))
> DF$Date <- as.Date(DF$Date)
> 
> aggregate(DF["z"], list(yearmon = format(DF$Date, "%Y-%m")), mean)
> 
> 
> 
> On 4/23/07, Michel Schnitz <michel.schnitz at web.de> wrote:
> 
>> Hello,
>>
>> is there a way to use the aggregate function to calculate monthly mean
>> in case i have one row in data frame that holds the date like
>> yyyy-mm-dd? i know that it works for daily means. i also like to do it
>> for monthly and yearly means. maybe there is something like aggregate(x,
>> list(Date[%m]), mean)?
>> the data frame looks like:
>>
>> Date            Time    z
>> 2006-01-01      21:00   6,2
>> 2006-01-01      22:00   5,7
>> 2006-01-01      23:00   3,2
>> 2006-01-02      00:00   7,8
>> 2006-01-02      01:00   6,8
>> 2006-01-02      02:00   5,6
>> .
>> .
>> .
>> 2007-03-30      22:00   5,2
>> 2007-03-30      23:00   8,3
>> 2007-03-31      00:00   6,4
>> 2007-03-31      01:00   7,4
>>
>> thanks for help!
>> -- 
>> Michél Schnitz
>> michel.schnitz at web.de
>>
>> ______________________________________________
>> R-help at stat.math.ethz.ch mailing list
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>> PLEASE do read the posting guide 
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
> 

-- 
Michél Schnitz
michel.schnitz at web.de

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