'Below'

[mar0000]

How would I be able to say something like "if row2 BELOW row1 then flag=0"

[PaigeMiller]

What does "below" mean? Does it mean less than?

Are row1 and row2 names of variables, or are they actually referring to different rows?

[mar0000]

Row 1 and 2 are actually different rows. My variable name is 'Type' and if Type = '2' then flag=1. I want to say if Type = '5' and is below Type = '2' that has flag = 1 then flag = 0. If Type = '5' and is below Type = '2' when flag is 0 then the flag should be 1. I want to base Type '5' off of Type '2.' Whatever Type 2 has flagged, I want type 5 to do the opposite

[mar0000]

This may make more sense: if Type 2 is flagged 1, I want Type 5 to flag 0. If Type 2 is flagged 0, I want Type 5 to flag 1.

[Kurt_Bremser]

PLEASE

supply example data in usable form (data step(s) with datalines), so we all don't waste time guessing what you have and what you want.

[mar0000]

Data have;
Type;
1
2
5
3
4
5

;

data want;
set have;
if type = '2' then flag = 1;

I want to say: if type = 2 and flag = 1 then when type = 5, the flag should be 0. If type = 5 is by itself (such as the last line of data), then the flag should be 1.

[Kurt_Bremser]

In case I forgot to mention: A WORKING data step that creates a dataset, and not just a log full of ERRORs.

[PaigeMiller]

---

@mar0000 wrote:
This may make more sense: if Type 2 is flagged 1, I want Type 5 to flag 0. If Type 2 is flagged 0, I want Type 5 to flag 1.

---

So what does this have to do with rows? Can you please show us an example data set, and then show us the desired output?

[mar0000]

Desired output 

Type Flag

1        1

2        1

5        0

3        1

4        1

5        1

[ed_sas_member · Accepted solution]

Hi @mar0000 

Does the following code meet your expectations?

The LAG() function retrieves the value from the previous row.

data want;
	set have;
	flag = 1;
	_lag = lag(Type);
	if (Type=2 and _lag=5) or (Type=5 and _lag=2) then flag=0;
	drop _lag;
run;

Best,

[Kurt_Bremser]

So you seem to mean:

when a type of 5 immediately follows a type of 2, flag should be 0, otherwise it should be zero?

If that is the case:

data want;
set have;
flag = not (type = 5 and lag(type) = 2);
run;