Using user-defined “for loop” function to construct a data frame

Question

I am trying to generate a data frame based on a user-defined function. My problem is that in the output only the first row is being filled. Here is an example of the functi

Answer 1

There are two problems with the function:

1. You're overwriting Col_T with all NAs as the first statement inside the for loop.
2. You're returning from the function inside the for loop.

Rewrite it as follows:

myfunc <- function(X, system, Title ) {
    Col_T <- data.frame(matrix(NA, ncol=length(X), nrow=4 ));
    for (i in 1:4)
        Col_T[i,] <- colSums(X[which(df$yr==i & df$cs==system),]);
    return(Col_T);
};