Accumulating total variable

[pchen002]

Given the SAS data set ONE:

ONE

XYZ

1 A 27

1A 33

1B 45

2A 52

2B 69

3B 70

4A 82

4C 91

The following SAS program is submiitted:

data two;

set one;

by x y;

if first.y;

run;

proc print data =two noobs;

run;

Hi I have tried to read this data into SAS however realising only the row "1A 33" is missing in the output data, why is it so?

[Astounding]

Here's a program you can run, to try to understand why:

data two;

set one;

by x y;

f_x = first.x;

f_y = first.y;

l_x = last.x;

l_y = last.y;

run;

proc print data=two;

run;

[ballardw]

How many combinations of X and Y in your data are duplicated?

Or do you find it easier to identify X an Y combinations that are unique?

How do they compare to the X Y combination that did not appear in the output?