Extract words from macro variable

[Ujjawal]

Is there a way we can extract number of words from a macro variable?

For example :

%let var = Balance Years_Since_Active Field1 Field2;

I want to extract first 3 from this list.

Note : In reality, the list is really big. It contains almost 800 words. I wanted to extract first 100 words. After that, I would like to extract from 101 to 200 and so on. Hence, the solution should be dynamic in such a manner user can specify lower limit i.e. 1 and upper limit i.e. 100. = SCAN(&var, (1:100), ' '). 

[SASKiwi]

%let var = Balance Years_Since_Active Field1 Field2;
%let word_count = %sysfunc(countw(&var));
%put word_count = &word_count;

[Astounding]

Can you guarantee that the same word will never appear twice within the list?  That could impact what tools will work.

[Ujjawal]

Yes the same word will never come twice within the list.

[Astounding · Accepted solution]

Given that the same word never appears twice ...

It's probably a little easier to work with a DATA step instead of macro language.  But all of this logic could be done with a macro if necessary.

%let first_word = 5;

%let last_word = 10;

%let var = some list of a great many words that do not contain any repeats;

data _null_;

p1 = scan("&var", &first_word, ' ');

p2 = scan("&var", &last_word, ' ');

if p1 > ' ' and p2 > ' ';

position1 = findw("&var", strip(p1));

position2 = findw("&var", strip(p2));

subset_of_words = substr("&var", position1, position2 - position1 + length(p2));

call symputx('subset_of_words', subset_of_words);

run;

%put &subset_of_words;

It's untested code, but should be fine.  At least the number of tools used is fairly small if you need to review any of them.

Good luck.

[Reeza]

It's possibly more efficient to toss the list into a data step and then query it via either a data step or proc sql. At least it might be easier to understand 🙂