creating blocks

[gp123]

I need to create a block variable to keep a tab on changing doses.

subject dose
10002 10MG
10002 10MG
10002 20MG
10002 10MG
10002 10MG

10004 10MG
10004 10MG
10004 10MG
10004 20MG
10004 20MG

I want the final dataset to look like as follows.

subject dose block
10002 10MG   1
10002 10MG   1
10002 20MG   2
10002 10MG   3
10002 10MG   3

10004 10MG   1
10004 10MG   1
10004 10MG   1
10004 20MG   2
10004 20MG   2

any thoughts?

[Reeza · Accepted solution]

BY groups + FIRST, this assumes your data is sorted as shown. 

data want;
set have;
by subject dose notsorted;

if first.subject then block=0;
if first.dose then block+1;

run;

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@gp123 wrote:

I need to create a block variable to keep a tab on changing doses.

subject dose
10002 10MG
10002 10MG
10002 20MG
10002 10MG
10002 10MG

10004 10MG
10004 10MG
10004 10MG
10004 20MG
10004 20MG

I want the final dataset to look like as follows.

subject dose block
10002 10MG   1
10002 10MG   1
10002 20MG   2
10002 10MG   3
10002 10MG   3

10004 10MG   1
10004 10MG   1
10004 10MG   1
10004 20MG   2
10004 20MG   2

any thoughts?

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