SApply versus for loop for list of data.frames

On Oct 12, 2010, at 12:16 AM, rivercode wrote:

Hi,

I am trying to find the total number of rows for a list of  
data.frames and
want to know if there is a better way than using a loop like:

df = { list of data.frame with varying number of rows...each one  
has a

column called "COL" }

r = 0
for (i in 1:length(df)) {

+ r = r + length(n[[i]]$CON)
+ }

r

6000123   <----  number of rows.

r <- lapply(df, NROW)
r

-- 
David.