topic Re: Find content of variable in another variable in SAS Programming

Find content of variable in another variable

Jedrzej — Wed, 03 Feb 2021 19:33:00 GMT

Hi, I want to create variable flag which will give Y if number from variable A will be in variable B

A	B	Flag
2	1;2;3;4;5	Y

I've tried index, find but nothing works...

thank you in advance

Re: Find content of variable in another variable

ballardw — Wed, 03 Feb 2021 19:41:48 GMT

Is A numeric or character?

If it is numeric then how did you create a character version to use the Index function with?

If you try to use a numeric variable in the Index function then the conversion to character will use a default format and usually results in leading blanks. So the value almost never is found.

You need to control the conversion to character as in:

data junk;
   a=2;
   b="1;2;3;4;5";
   flag = index(b,a);
   flagb = index(b,strip(put(a,best.)));
run;

Flag is 0, i.e. a not found because of the conversion issue.

Flagb is 3, i.e. the 2 was found in the 3rd position.

Personally I would use

data junk;
   a=2;
   b="1;2;3;4;5";
   flag = ( index(b,strip(put(a,best.))) > 0);
run;

Which creates a numeric value of 1, for true, and 0 for false on the find. A custom format could be used if you really need to see "Y". The coding I propose is more flexible for a number of calculations: Sum of flag is the number of 1, mean is the percent of 1s and you can write expressions like "if flag then <do something>" as SAS will treat 1 as true.

Re: Find content of variable in another variable

Jedrzej — Wed, 03 Feb 2021 19:44:32 GMT

A and B are char not numeric

Re: Find content of variable in another variable

Shmuel — Wed, 03 Feb 2021 19:47:43 GMT

Is variable A numeric or character ?

I suppose variable B is char type.

If A is numeric transform it into char by strip(put(a,best8.));

then you can use any of the next functions:

1) if index(b,a) then flag='Y';

2) if findw(b,a) then flag='Y';

Re: Find content of variable in another variable

Jedrzej — Wed, 03 Feb 2021 20:10:34 GMT

i don't know why it doesn't work on my dataset, when i do some dummy dataset it's ok.

index finds only the last number of sequence, for example 1;2;3;4;5 it gives Y flag to 5 but when it's for example 3 it does not.

Maybe it's something to do with delimiters?

Re: Find content of variable in another variable

ballardw — Wed, 03 Feb 2021 20:29:04 GMT

Example data

Instructions here: https://communities.sas.com/t5/SAS-Communities-Library/How-to-create-a-data-step-version-of-your-data-AKA-generate/ta-p/258712 will show how to turn an existing SAS data set into data step code that can be pasted into a forum code box using the <> icon or attached as text to show exactly what you have and that we can test code against.

And the actual code you are attempting.

Note: if you have LEADING spaces in a value like " 2", then you won't find the value in "1;2;3" because the string you search does not have the leading space. If you have trailing non-printable characters other than spaces you will have the same problem.

data example;
   a='2';
   a2 = ' 2';
   a3=cats('2',"09"x);
   b='1;2;3;4;5';
   first= index(b,a);
   second= index(b,a2);
   third= index(b,a3);
run;

The A3 value has a TAB character after the 2. When you print or examine the data in a SAS table viewer you won't see the tab and might think that is all there is to the value. But it does not match the '2' in the searched string.

So specific data is needed to diagnose what is going on. Since you say it finds "5" I suspect something along the lines of intermittent values with leading spaces.

Re: Find content of variable in another variable

Jedrzej — Wed, 03 Feb 2021 20:50:48 GMT

i had trailing blanks in var A, thank you

Re: Find content of variable in another variable

Shmuel — Wed, 03 Feb 2021 20:54:00 GMT

what is the length of variable A ?

Re: Find content of variable in another variable

Jedrzej — Wed, 03 Feb 2021 21:10:13 GMT

Yes