[Gretl-devel] feature request: overload lags() and perhaps the foreach loop

Hi, I propose to overload the lags() function to accept not only a scalar lag value, but alternatively a vector/matrix where the elements specify which lags we want in the returned list. Here's a hansl function that does what I have in mind: <hansl> function list getCertainLags( matrix idx, const list inp, bool bylag[0]) # returns a list with those lags of 'inp' specified by 'idx' elements idx = vec(idx) # ensure col vector list out = null loop i=1..rows(idx) lag = idx[i] list temp = lags(lag, inp, bylag) # watch out for the special case of lag 1 list templess1 = lag==1 ? null : lags( lag - 1, inp, bylag) list out = out || (temp - templess1) endloop return out end function </hansl> And then I also have an unrelated and more fundamental feature suggestion: How about extending the foreach loop to also cover matrices and perhaps even arrays? So instead of the common thing: loop i=1..rows(inputvector) v = inputvector[i] ... one would do: loop foreach v inputvector ... and similarly for arrays. This is of course pure syntactic sugar -- and I also admit that this feels very pythonic, but I think it's not only present in Python. Don't know how difficult it would be to implement. After all, currently foreach is only for internal gretl strings. thanks, sven