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Why is my code not flagging variables properly?

Frequent Contributor
Posts: 88

Why is my code not flagging variables properly?

I have a data set and I am trying to flag all variables that have the word "treatment" or "tx" with a 1 else 0. However, there are some observations which have the following description: "Supplies-treatment" or "supplies-tx". For these, I DO NOT want them to be flagged with a 1.


Here is my code:


data flagtx;
set flagtxdc;
if prxmatch("m/tx|treatment|treat/oi",description) > 0 then tx=1;
else tx=0;


this works perfectly! When I run a proc freq I see that there are 33314 obs flagged with a 1.


But then I want to unflag all the descriptions that have the word "supplies" in them. In order to accomplish this I thought I could use a prxmatch as above but on the new dataset I just created with all the words "treatment" flagged with 1, and when it came across any descriptions with "supplies" it would flag it as a 0. I used this code next after running the above code to accomplish the aforementioned:


data flagtxsupplies;
set flagtx;
if prxmatch("m/supplies/oi",description) > 0 then tx=0;
else tx=1;


However, when I run a proc freq, I see that it has incorrectly flagged my variables somehow. Instead of having LESS than 33314 obs flagged with a 1 (which should be the case because I am eliminating "supplies-treatment") I actually have MORE obs that have been flagged with a 1. 64174 to be exact!


I did a proc print on 100 obs but everything looks good..what is going on?? What is my code doing exactly?


Thank you

Super User
Posts: 17,864

Re: Why is my code not flagging variables properly?

Rethink your else statement. 

Respected Advisor
Posts: 4,651

Re: Why is my code not flagging variables properly?

Your second step overwrites tx for every obs. So the end result is just the last test, i.e. anything not supplies is flagged. 


In a single step:


data flagtx;
set flagtxdc;
tx = 0;
if prxmatch("m/tx|treatment|treat/oi", description) > 0 then 
	if prxmatch("m/supplies/oi", description) = 0 then tx = 1;
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