[R] separating data into columns

[Jannis]

I am sure there is a more sophisticated way, but I would do it like this:

hourindex <- round(as.numeric(YYMMDDHHmm)/100,digits=0)

hourly.means <- aggregate(dataset,hourindex,mean)

For aggregate you just need an index with the length of the amount of 
rows that your dataset has, that assigns a unique number to each hour.

Still I am sure there are ways to extract, for example, the amount of 
hours since origin from a zoo object and use this as the hourindex.

HTH
Jannis
sheck at ucar.edu schrieb:
> Hi All-
>
> I have been trying to separate data into columns - specifically the 
> date - and then aggregate the rest of the data to calculate summer 
> hourly means. However, now I would like to calculate hourly means just 
> over one day at a time.  And, I am not able to figure out how to do 
> this. I read some help files that I think indicated that I can only 
> use the method below for months, years and quarters. Perhaps just 
> separating the date into the following columns would work - Yr Mon Day 
> Hr Min???
>
> I originally used "zoo" and "chron" as follows for the monthly means:
>
>
> library(zoo)
> library(chron)
>
> z <- read.zoo("C:/R/SPL JJA 2006 2008.txt", header = TRUE, na.strings 
> = -999,
> format = "%y%m%d%H%M", FUN = as.chron,
> colClasses = c("character", rep("numeric", 10)))
>
> mph <- z[months(time(z)) %in% c("Jun", "Jul", "Aug"),]
> mphagg <- aggregate(mph, hours, mean)
>
>
> Here is a sample data set:
>
> YYMMDDhhmm   Precip  mph   Deg    DegF   Fuel   Rel   volts   DegMx  
> mphgust wm
> 0606010000   0.00    4.6   97.5   42.1   -999   39.5   -999   -999    
> 5.2    0.3
> 0606010005   0.00    4.6   97.6   42.0   -999   38.8   -999   -999    
> 5.7    0.3
> 0606010010   0.00    2.6   97.6   41.9   -999   36.9   -999   -999    
> 3.5    0.3
> 0606010015   0.00    2.3   97.6   41.8   -999   37.1   -999   -999    
> 3.7    0.3
> 0606010020   0.00    1.8   97.6   41.5   -999   36.3   -999   -999    
> 1.8    0.3
> 0606010025   0.00    1.8   97.6   41.1   -999   36.1   -999   -999    
> 1.8    0.3
> 0606010030   0.00    1.8   97.6   40.8   -999   36.1   -999   -999    
> 1.8    0.3
> 0606010035   0.00    1.8   97.6   40.4   -999   35.3   -999   -999    
> 1.8    0.3
> 0606010040   0.00    1.8   97.7   40.1   -999   36.0   -999   -999    
> 1.8    0.3
> 0606010045   0.00    1.8   97.7   39.7   -999   36.7   -999   -999    
> 1.8    0.3
> 0606010050   0.00    1.8   97.7   39.3   -999   37.3   -999   -999    
> 1.8    0.3
> 0606010055   0.00    1.8   97.7   38.9   -999   38.0   -999   -999    
> 1.8    0.3
> 0606010100   0.00    1.8   97.7   38.6   -999   38.9   -999   -999    
> 1.8    0.3
>
> Any help is appreciated-
>
> Thanks-
>
> Sherri Heck
> University of Colorado
>
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