[R] adding date/time stamp

[Sherri Heck]

Dear All-

I have a dataset that is comprised of the following (LST = yymmddhhMM):



     LST   in     mph    Deg   DegF  DegF2    %    volts   Deg    mph2   
w/m2
0509010000   0.00    7.8  216.9   45.1   -999   24.4   -999   -999   
10.6    0.2
0509010005   0.00    8.6  206.6   45.1   -999   25.2   -999   -999   
11.7    0.2
0509010010   0.00    7.8  199.2   44.9   -999   25.4   -999   -999   
12.8    0.2
0509010015   0.00    7.7  197.4   44.8   -999   25.4   -999   -999   
10.4    0.2
0509010020   0.00    7.6  203.9   44.8   -999   25.3   -999   -999   
10.0    0.2
0509010025   0.00    9.3  200.9   44.9   -999   25.3   -999   -999   
11.8    0.2
0509010030   0.00    9.4  200.3   44.7   -999   25.5   -999   -999   
12.2    0.2
0509010035   0.00   10.0  199.2   44.6   -999   25.9   -999   -999   
13.0    0.2
0509010040   0.00    9.5  201.5   44.5   -999   25.9   -999   -999   
13.3    0.2
0509010045   0.00   10.8  200.4   44.5   -999   26.1   -999   -999   
13.0    0.2
0509010050   0.00   11.8  198.4   44.5   -999   26.1   -999   -999   
13.3    0.2
0509010055   0.00   11.0  197.4   44.5   -999   25.5   -999   -999   
13.3    0.2
0509010100   0.00    9.7  202.0   44.6   -999   25.1   -999   -999   
13.0    0.2
0509010105   0.00    9.0  215.1   44.7   -999   24.9   -999   -999   
12.2    0.2
0509010110   0.00   10.1  223.1   44.6   -999   25.1   -999   -999   
13.2    0.2
0509010115   0.00   10.4  231.2   44.5   -999   25.5   -999   -999   
12.0    0.2
0509010120   0.00   11.0  237.4   44.2   -999   25.9   -999   -999   
11.7    0.2
0509010125   0.00   10.6  241.0   44.2   -999   26.0   -999   -999   
11.8    0.2
0509010130   0.00   11.1  242.2   44.1   -999   26.2   -999   -999   
12.2    0.2
0509010135   0.00   10.6  240.0   44.0   -999   26.5   -999   -999   
11.5    0.2
0509010140   0.00   10.1  241.0   44.0   -999   26.4   -999   -999   
11.5    0.2
0509010145   0.00    9.8  243.2   44.0   -999   26.6   -999   -999   
10.7    0.2
0509010150   0.00    9.3  240.3   43.9   -999   27.0   -999   -999   
10.0    0.2
0509010155   0.00    9.3  239.2   43.8   -999   26.8   -999   -999   
10.0    0.2
0509010200   0.00    9.2  240.1   43.8   -999   26.6   -999   -999    
9.8    0.2
0509010205   0.00    9.0  240.0   43.8   -999   26.6   -999   -999    
9.4    0.2
0509010210   0.00    9.2  245.0   43.9   -999   26.3   -999   -999    
9.8    0.2
0509010215   0.00    9.4  253.2   44.1   -999   26.4   -999   -999   
10.6    0.2

The data are recorded in 5 minute intervals and I would like to condense 
it into hourly means for "mph". For example,  I would like the hourly 
avg of mph so that the output would be as follows:

Year Month Day Hour mph
2005 1 1 0 12
2005 1 1 1 7
2005 1 1 2 11, etc.


It seems I am able to get the averages but not output the corresponding 
date/time stamp.  From looking at previous help questions, I think I 
need to us "ts" and "aggregate".   Gabor taught me how to convert the 
date/time stamp to an easier to manage format (his help is shown 
below).  This is what I have so far. 

library(zoo)
library(chron)

z <- read.zoo("SPL 2005 2008 met data 5 min wout full hdr.txt", header = 
TRUE, na.strings = -999,
format = "%y%m%d%H%M", FUN = as.chron,
colClasses = c("character", rep("numeric", 10)))     

z.ts <- ts(z, frequency=12)    #avging 5 min intervals to get hourly 
avg.     
ww <- matrix(aggregate(z.ts[,2], FUN=mean))

any thoughts as to how to add the time stamp is greatly welcomed!

sherri heck