R help - Dec 2008 - simple list question

I'd appreciate some tips, I'm  making a simple mistake   trying to
extract elements from a list of fit objects.

  The following command works,  coef( cph.list[[1]] )  ,.... coef(
cph.list[[3]] ) and so forth.  These  extract regression coefficients
from the appropriate list element. 

  When I try to run this inside  a for loop, or an lapply
(lapply(cph.list,coef))  I get this error message


   > for (ii in (1:22)){
+  cat(ii,fill=T) 
+   print(coef( cph.list[[ii]] ))
+ 
+ }
1
Error in object$coefficients : $ operator is invalid for atomic vectors

Suggestions appreciated. 
Thanks in advance.




    Chris Barker, Ph.D.
  Statistical Consultant


	[[alternative HTML version deleted]]

Barker, Chris wrote:
> 
> 
>   I'd appreciate some tips, I'm  making a simple mistake   trying
to
> extract elements from a list of fit objects.
> 
>   The following command works,  coef( cph.list[[1]] )  ,.... coef(
> cph.list[[3]] ) and so forth.  These  extract regression coefficients
> from the appropriate list element. 
> 
>   When I try to run this inside  a for loop, or an lapply
> (lapply(cph.list,coef))  I get this error message
> 
> 
>    > for (ii in (1:22)){
> +  cat(ii,fill=T) 
> +   print(coef( cph.list[[ii]] ))
> + 
> + }
> 1
> Error in object$coefficients : $ operator is invalid for atomic vectors
> 
> 
No obvious mistake/not reproducible: are you sure that all 22 elements
of the list are really linear model fits?  The following made-up example
works just fine for me.
What are the results of sapply(cph.list,class) ?

x <- 1:100
cph.list <- list()
set.seed(1001)
for (ii in 1:22) {
  y <- rnorm(100,1+2*x,sd=1)
  cph.list[[ii]] <- lm(y~x)
}
  
for (ii in 1:22) {
  cat(ii,fill=TRUE)
  print(coef(cph.list[[ii]]))
}

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