SAS programming "golf": highest digit in a string of digits

[FreelanceReinh]

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@ProcWes wrote:
What does the -9 modifier do here?

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It instructs the FINDC function to start the search at the 9th character (of the first argument) with search direction – because of the negative sign – from right to left.

[ProcWes]

Ok, so if c was 1-8, it'd be -8 and if it were 1234567890 it would be -10. Correct?

[FreelanceReinh]

No. If the first argument of FINDC (not c) was '12345678' the modifier -8 could be used, but in this case obviously FINDC would fail to find any digit '9' in '12345678'. So, if c had contained a digit '9' the result would have been incorrect (0) with that code modification. Similarly, with '1234567890' and -10 the '0' in c would have been found first, again leading to an incorrect answer (10, which is absurd) to the original question.

[AhmedAl_Attar]

Here is another Base SAS approach using the APP functions

data have;
    array ct [20] $1 _temporary_ ; /* Changing the size of the array elements, allows you to compare 2,3,.. digits */
    call pokelong ("000112010302",addrlong(ct[1]),length("000112010302"));
    max=max(of ct{*});
    put max=;
run;

Thanks,

Ahmed

[SASJedi]

Maybe not the shortest, but I haven't seen POKE used in a long time. That was fun! 🙂

[Tom]

How about this:

  do i=9 to 0 by -1 while (x=.);
    if indexc(k,put(i,z1.)) then x=i ;
  end;

223  data have;
224    k="000112010302";
225    do i=9 to 0 by -1 while (x=.);
226      if indexc(k,put(i,z1.)) then x=i ;
227    end;
228    put k=:$quote. x= ;
229  run;

k="000112010302" x=3

[Tom]

Are we allowed to assume we have an autocall library?

608  data want;
609    x=%x(000112010302);
610    put x=;
611  run;

x=3

[SASJedi]

You CAN, but the lines of code in the autocall macro have to count, too... 😄

[novinosrin]

data have;
  input k $12.;
cards;
000112010302
0
1
2
3
4
5
6
7
8
9
0123456789
.
;

data w;
set have;
k1=compress('9876543210',k,'k');   
want=char(k1,1);
run;

cleaned further with first function wrapper:

data w;
set have;
want=first(compress('9876543210',k,'k'));  
run;

[SASJedi]

That's a pretty sweet solution 🙂

[novinosrin]

@SASJedi  Thank you Sir!

[ChrisHemedinger]

The responses here are great, and I've learned a lot. 

I've summarized the best so far in a new blog post, SAS code golf: find the max digit in a string of digits.

Shoutouts to @novinosrin, @hashman, @FreelanceReinh, @AhmedAl_Attar, and @ChanceTGardener.

[FreelanceReinh]

Nice blog post, Chris. Thanks for the notification.

Yesterday, I was about to edit my initial post once again and delete the useless semicolon from my one-line suggestion. But I thought this minor correction wouldn't justify another edit, because that %SYSFUNC call didn't exactly address the original question (involving a "character var") anyway. Of course, I would have corrected it, had I known that this code would be further disseminated. Now, the "winner, in terms of concision" contains an obviously redundant character ...

So, lesson learned: Edit every bit of posted code until it's perfect.

[ChrisHemedinger]

"The perfect is the enemy of the good."

That's my justification for cranking out large volumes of mediocre-but-functional code (and maybe applies to blog posts too...)

[FreelanceReinh]

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@ChrisHemedinger wrote:

That's my justification for cranking out large volumes of mediocre-but-functional code (and maybe applies to blog posts too...)

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Chris, I've just noticed that you didn't copy (or rather type out) my one-liner correctly in your blog: The second argument of FINDC is missing a leading zero! The same mistake happened in what seems to be (but in fact isn't) a quote from @novinosrin's code. In the code section of the "Apprendix" (sic!) both versions of the string are present.