creating conditional means

Hi Gabor,

Thank you for your help.  I think I need to clarify
a bit more.  I am 
trying to say

average all 2pms for months march + april + may (for
example). I hope this is clearer.  

here's a larger subset of my data set:

year, month, hour, co2(ppm), num1,num2

2006 1 0 384.2055 14 14
2006 1 1 384.0304 14 14
2006 1 2 383.9672 14 14
2006 1 3 383.8452 14 14
2006 1 4 383.8594 14 14
2006 1 5 383.7318 14 14
2006 1 6 383.6439 14 14
2006 1 7 383.7019 14 14
2006 1 8 383.7487 14 14
2006 1 9 383.8376 14 14
2006 1 10 383.8684 14 14
2006 1 11 383.8301 14 14
2006 1 12 383.8058 14 14
2006 1 13 383.9419 14 14
2006 1 14 383.7876 14 14
2006 1 15 383.7744 14 14
2006 1 16 383.8566 14 14
2006 1 17 384.1014 14 14
2006 1 18 384.1312 14 14
2006 1 19 384.1551 14 14
2006 1 20 384.099 14 14
2006 1 21 384.1408 14 14
2006 1 22 384.3637 14 14
2006 1 23 384.1491 14 14
2006 2 0 384.7082 27 27
2006 2 1 384.6139 27 27
2006 2 2 384.7453 26 26
2006 2 3 384.9224 28 28
2006 2 4 384.8581 28 28
2006 2 5 384.9208 28 28
2006 2 6 384.9086 28 28
2006 2 7 384.837 28 28
2006 2 8 384.6163 27 27
2006 2 9 384.7406 28 28
2006 2 10 384.7468 28 28
2006 2 11 384.6992 28 28
2006 2 12 384.6388 28 28
2006 2 13 384.6346 28 28
2006 2 14 384.6037 28 28
2006 2 15 384.5295 28 28
2006 2 16 384.5654 28 28
2006 2 17 384.6466 28 28
2006 2 18 384.6344 28 28
2006 2 19 384.5911 28 28
2006 2 20 384.6084 28 28
2006 2 21 384.6318 28 28
2006 2 22 384.6181 27 27
2006 2 23 384.6087 27 27


thanks you again for your assistance-

s.heck


Gabor Grothendieck wrote:

Try aggregate:


Lines <- "Year Month Hour co2 num1 num2
 2006   11    0 383.3709   28   28
 2006   11    1 383.3709   28   28
 2006   11    2 383.3709   28   28
 2006   11    3 383.3709   28   28
 2006   11    4 383.3709   28   28
 2006   11    5 383.3709   28   28
 2006   11    6 383.3709   28   28
 2006   11    7 383.3709   28   28
 2006   11    8 383.3709   28   28
 2006   11    9 383.3709   27   27
 2006   11   10 383.3709   28   28
"
DF <- read.table(textConnection(Lines), header =

TRUE)

aggregate(DF[4:6],
   with(DF, data.frame(Year, Qtr = (Month - 1) %/%

3 + 1, Hour)),

   mean)

On Dec 1, 2007 3:57 PM, Sherri Heck

<sheck at ucar.edu> wrote:

Hi all-

I have a dataset (year, month, hour, co2(ppm),

num1,num2)

[49,] 2006   11    0 383.3709   28   28
[50,] 2006   11    1 383.3709   28   28
[51,] 2006   11    2 383.3709   28   28
[52,] 2006   11    3 383.3709   28   28
[53,] 2006   11    4 383.3709   28   28
[54,] 2006   11    5 383.3709   28   28
[55,] 2006   11    6 383.3709   28   28
[56,] 2006   11    7 383.3709   28   28
[57,] 2006   11    8 383.3709   28   28
[58,] 2006   11    9 383.3709   27   27
[59,] 2006   11   10 383.3709   28   28

that repeats in this style for each month.  I

would like to compute the

mean for each hour in three month intervals.
i.e.  average all 2pms for each day for months

march, april and may. and

then do this for each hour interval.
i have been messing around with 'for loops' but

can't seem to get the

output I want.

thanks in advance for any help-

s.heck
CU, Boulder