[R] separating data into columns

[Gabor Grothendieck]

This calculates hourly means:

> aggregate(z, trunc(time(z), "01:00:00"), mean)
                    Precip   mph    Deg DegF Fuel      Rel volts DegMx
 mphgust  wm
(06/01/06 00:00:00)      0 2.375 97.625 40.8   NA 37.00833    NA    NA
2.708333 0.3
(06/01/06 01:00:00)      0 1.800 97.700 38.6   NA 38.90000    NA    NA
1.800000 0.3


Also note that in the examples section of help(read.zoo) is an example
of aggregating as you read the data in using read.zoo.


On Sun, Jun 6, 2010 at 7:40 PM,  <sheck at ucar.edu> wrote:
> 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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