[R] Two brief questions concerning sapply. Can anyone please help?!

[afpjt@uaa.alaska.edu]

To anyone who can help:

I have two brief questions concerning sapply.  Following below is the 
code for my example.  The two problems are described at the end of the 
code:


site <- rep(2:6, each = 12) 

tillage <- rep(c(1,-1), each = 6, times = 5) 

carbon <- c(18.23, 16.06, 17.81, 16.07, 17.26, 17.08, 
            14.92, 15.88, 12.11, 14.23, 16.99, 13.57, 
            20.34, 20.3,  18.78, 19.91, 18.43, 20.8,  
            18.98, 19.24, 18.18, 16.69, 19.72, 18.35, 
            36.83, 32.85, 30.21, 31.58, 34.35, 31.4,
            27.72, 29.9,  25.97, 27.63, 28.13, 27.68,
            23.11, 24.32, 21.87, 29.18, 26.52, 23.25,
            24.16, 17.62, 19.62, 20.5,  21.01, 25.62,
            25.73, 23.42, 25.17, 23.76, 23.27, 23.37,
            20.89, 19.93, 19.24, 19.4,  22.09, 18.96)

junk <- interaction(tillage, site)

nr.carbon <- sapply(split(carbon, junk), function(x) mean(x))

> nr.carbon

    -1.2      1.2     -1.3      1.3     -1.4      1.4     -1.5      1.5 
14.61667 17.08500 18.52667 19.76000 27.83833 32.87000 21.42167 24.70833 
    -1.6      1.6 
20.08500 24.12000 

PROBLEM 1 -- How do I sort nr.carbon such that 1.2 comes before -1.2, 
1.3 comes before -1.3, etc.  

PROBLEM 2 -- How do I get rid of the pesky names automatically assigned 
by sapply so that I only have the data in nr.carbon? 

Thanks in advance to those who reply!

--------------------------------------
Philip Turk
Assistant Professor of Applied Statistics
Department of Mathematical Sciences
University of Alaska Anchorage
CAS #154N, 3211 Providence Drive
Anchorage, Alaska  99508
Phone: 907-786-1163  
Fax: 907-786-6162
Email: afpjt at uaa.alaska.edu
Web Page: http://afpjt.uaa.alaska.edu