Please I need some help using R to 
analyze my data. What I
would like to do is to repeat the same basic process (e.g. linear regression
between wood density and distance from pith) for at least 240 data 
subsets
within the main data-frame. Within the main data-frame, these data subsets will be defined by three 
variables
namely,  species, individual and core (i.e. 20 species, at least 6 
individuals
of each species, and 2 cores from each individual).  Whereas I can write
the code to carry out this process for each subset, I am unable to 
successfully
instruct R to automatically carry out the process for each of these 
subsets (perhaps using loops). So to illustrate what I have done so far 
with the codes
below I was able to run a regression
 analysis for core ‘a’ of individual 1 in
the species “Apeime”. But rather than do this 240 times, I would like to
 tell R
to repeat the process automatically using loops or any method that 
works.  

   

Code: 

   

RG2<-BCI[BCI$Species == "APEIME" 
&
BCI$Individual == 1 & BCI$Core == "a", ] 

> plot(x=RG2$DP..cm., 
y=RG2$WD..g.cm3,
xlab="Distance from pith cm", main="APEIME1a",
ylab="Wood density g/cm3") 

> 
RG2lm<-lm(RG2$WD..g.cm3~RG2$DP..cm.) 

> summary(RG2lm) 

   

Thanks 

   

Oyomoare




      
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