Do Loop

[Tal]

ok ,when the loop checks for x(5) or "e" he checks into 10  20  30 999  50 or into 10  20  30 0  50?

[Tal]

i mean 10  20  30 999  50 or 10  20  30 .  50?

[art297]

When the loop checks for x(5) it is only checking for e or 50.  Since 50 isn't equal to 999 it is left at 50.

[art297]

It might help if you did the same thing without either a loop or array.  Your code is doing the same thing as below:

data old;
input a b c d e;
datalines;
10  20  30 999  50
50  40 999  20  10
999   1   1   1 999
;
run;

data new;

set old;

if a eq 999 then a=.;

if b eq 999 then b=.;

if c eq 999 then c=.;

if d eq 999 then d=.;

if e eq 999 then e=.;

run;

First, it is doing it for the first row (i.e., 10 20 30 99 and 50), then outputting the results, then doing it for the 2nd row and outputting the results, and then again for the third row.

[Tal]

i could get the results using different methods but i wanted to understand how loop works with set and at the end i got stuck.

ok,a not 999 so sas writes the observation

same for b and c.Then d=999 so it gets set to missing and sas writes that observation too then when the loops checks for e,last element not 999 nothing changes and sas writes the 5th observation but with the missing value for d again.So it looked like the loop checked 10 20 30 . 50 for the value of d and not 10 20 30 999 50. Probably i am missing something huge about do loops and the output statement.

	1	10	20	30	999	50
	2	10	20	30	999	50
	3	10	20	30	999	50
	4	10	20	30	.	50
	5	10	20	30	.	50
	6	50	40	999	20	10
	7	50	40	999	20	10
	8	50	40	.	20	10
	9	50	40	.	20	10
	10	50	40	.	20	10
	11	.	1	1	1	999
	12	.	1	1	1	999
	13	.	1	1	1	999
	14	.	1	1	1	999
	15	.	1	1	1	.

[art297]

For the first record:

when the loop checks x(i) and i=1 it is ONLY checking the value of a.  Since the loop contained an output statement it was outputing the values of a, b, c, d and e.

when the loop checks x(i) and i=2 it is ONLY checking the value of b.  Since the loop contained an output statement it was outputing the values of a, b, c, d and e.

when the loop checks x(i) and i=3 it is ONLY checking the value of c.  Since the loop contained an output statement it was outputing the values of a, b, c, d and e.

when the loop checks x(i) and i=4 it is ONLY checking the value of d.  Since the value was 999 it chances the value of d to missing.  Since the loop contained an output statement it was outputing the values of a, b, c, d and e.

Finally, when the loop checks x(i) and i=5 it is ONLY checking the value of e.  Since the loop contained an output statement it was outputing the values of a, b, c, d and e.

Then, SAS goes on to the second record, etc.

[Tal]

and the value of d was set to  missing from before already and that's way that change reflects in the last output too.

Thank you both for lengthy bother

[Tom]

The SET statement is the one that is reading in values from the OLD dataset.

So on the first pass through the OLD dataset when you change D from 999 to missing it will stay missing until you read the second observation.

[Tal]

yaa thanks