On 13-12-21 6:50 PM, Duncan Murdoch wrote:
On 13-12-21 5:57 PM, Göran Broström wrote:
I was recently reminded on this list that
"Using 1:ncol() is bad practice (seq_len is designed for that purpose)"
(Ripley)
This triggers the following question: What is "good practice" for
2:ncol(x)? (This is not a joke; in a recursive situation it often makes
sense to perform the calculation for the start value i = 1, then
continue with a loop over the rest, "the Fortran way";)
I usually use
if (ncol(x) > 1)
for (i in 2:ncol(x)){
....
but I can think of
for (i in seq_len(x - 1)){
I <- i + 1
....
and
i <- 1
while (i < ncol(x)){
i <- i + 1
....
What is "good practice" (efficient and safe)?
for (i in seq_len(x - 1) + 1)
should be efficient and safe.
Oops, not safe when x is 0.
>
A little less efficient, but clearer would be
for (i in seq_len(x)[-1])
Duncan Murdoch
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