Hi,
May be this helps:
Using your function:
mapply(less,test,4)
#or
invisible(mapply(less,test,4))
#[1] 2 3
#[1] 3
#or
for(i in 1:ncol(test)){
less(test[,i],4)}
#[1] 2 3
#[1] 3
A.K.
Hi, I'm trying to figure out how to loop through columns in a matrix or
data frame, but what I've been finding online has not been very clear.
I've written the following simple function that I can use on a column to
extract all values that are less than a specified number. Consider the
following example using that function to extract all values less than 4
from column1 of the table "test"
> less <- function(x,y){print(x[which(x < y)])}
> test
column1 column2
1 2 3
2 3 4
3 4 5
> less(test[,1],4)
[1] 2 3
What I want to do is loop that function over all the columns
in the table. Note: I realize that this is a silly example and there
are better ways to do this particular function in R, so please don't
respond with better ways to extract values less than a given number. The
question that I am interested in is merely how do I loop over the
columns. If you could respond by modifying my silly function so that it
will loop, that would be the most helpful response. Thanks for the
advice!
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