An efficient way to Copying values in subsequent records - SAS

Question

I have a dataset that is grouped by category variables in the source data. For example:

Bar  | Foo1
     | Foo2
     | Foo3
Bar2 | Foo4
     | Foo5
     | Fo         


        

Answer 1

The lag function returns the last value that was passed to it when it was called, not the value that was last output.

You could do something like the following:

data want;
    set have;
    length last_parent $256;
    retain last_parent;

    if parent = "" then parent = last_parent;
    else last_parent = parent;

    drop last_parent;
run;

You would need to set the length of last_parent to the same length as parent to make sure nothing gets cut off.