Tricky Sorting--How to decide and subset only first combination of variables

[HarshadMadhamshettiwar]

Hi All,

I have to subset a large data set with multiple to parent to child item combination.

Of which I have to only subset the one which should belong to the first combination of the variables only.

Ex. One parent_item and multiple child_items and I just want to dynamically select the first of every combination. I TRIED SORT AND FIRST.VARIABLE AND LAST.VARIABLE BUT IN ALL THOSE CASES THE FIRST COMBINATION APPEARING INORIGINAL DATA SET MAY CHANGE BECAUSE OF SORTING. How can it be achieved.

parent_item	desc	child item	value
A11233	harry potter	a11233a	1200
A11233	harry potter	a11233a	565
A11233	harry potter	a11233a	45458
A11233	harry potter	a11233a	648
A11233	harry potter	a11233a	9889
A11233	harry potter1	a11233b	44
A11233	harry potter1	a11233b	44848
A11233	harry potter1	a11233b	10165
A11233	harry potter1	a11233b	4547
A11233	harry potter2	a11233b	7950
A11233	harry potter2	a11233c	6608
A11233	harry potter2	a11233c	54589
A11233	harry potter2	a11233c	445
A11233	harry potter2	a11233c	45
B11233	batman	b11233a	1200
B11233	batman	b11233a	565
B11233	batman	b11233a	45458
B11233	batman	b11233a	648
B11233	batman	b11233a	9889
B11233	batman1	b11233b	44
B11233	batman1	b11233b	44848
B11233	batman1	b11233b	10165
B11233	batman1	b11233b	4547
B11233	batman1	b11233b	7950
B11233	batman2	b11233c	6608
B11233	batman2	b11233c	54589
B11233	batman2	b11233c	445
B11233	batman2	b11233c	45

[Kurt_Bremser]

If you want to be consistent in selecting an observation out of a group, you need to define a rule and force that during the sorting step.

Everything you leave to chance will happen by chance.

IE if you want that the original order to be preserved:

data inter;
set have;
obsno = _N_;
run;

proc sort data=inter;
by parent_item desc child_item obsno;
run;

data want (drop=obsno);
set inter;
by parent_item desc child_item;
if first.child_item;
run;

[Astounding]

Here's an approach.  If it doesn't do exactly what you want, it's probably close enough that you can adjust it.

data want;

set have;

by parent_item notsorted;

if first.parent_item then first_child = child_item;

retain first_child;

if child_item = first_child;

drop first_child;

run;

[TapioKalmi]

Did you use EQUALS option with PROC SORT?
It should keep the original order of rows within the sort key value.