Output missing values between two lists

[jmmedina252]

I have two variables that should match, but some do not.  The variables are comma separated strings and if one list is missing values from the ideal list, I need it to output those values.

Have:

Animal      Days            Days_expected     

100            1,2,3,4         1,2,3,4,5

101            2,3,5            1,2,3,4,5

102            1,3,4,5         1,2,3,4,5

Want:

Animal      Days            Days_expected     Days_missing

100            1,2,3,4         1,2,3,4,5                  5   

101            2,3,5            1,2,3,4,5                  1,4

102            1,3,4,5         1,2,3,4,5                  2

[Tom · Accepted solution]

Just loop over the set of expected values and test if it appears or not.

data have;
  input Animal $ Days :$10. Days_expected :$10.;
cards;
100            1,2,3,4         1,2,3,4,5
101            2,3,5            1,2,3,4,5
102            1,3,4,5         1,2,3,4,5
;

data want;
  set have;
  length Days_missing $10;
  do index=1 to countw(days_expected,',');
    if not findw(days,scan(days_expected,index,','),',','T') then
      days_missing=catx(',',days_missing,scan(days_expected,index,','))
    ;
  end;
  drop index;
run;

[ballardw]

Generally placing multiple values into a single variable is a bad thing and this is an example.

Questions: Does the value of "Days_expected" ever actually change? Is it actually a variable in the dataset? If so, is it always going to be sequentially numbered values? 

With the example provided:

data have;
   infile datalines dlm='|';
   input Animal $ Days:$15. Days_expected :$15. ;
   length word $ 3 result $ 15;
   do i=1 to countw(days_expected,',');
      word = scan(days_expected,i,',');
      if findw(strip(days), strip(word),',')=0 
          then result=catx(',',result, word);
   end;
   drop i word;
datalines;
100|1,2,3,4|1,2,3,4,5
101|2,3,5|1,2,3,4,5
102|1,3,4,5|1,2,3,4,5
;

Strip is needed in a few places because we do not know the actual lengths of your variables or the maximum possible value(s) involved.

Countw counts how many elements are in the list. If Days_expected is not an actual variable then use a quoted list such as "1,2,3,4,5" every where the variable Days_expected appears.

Scan pulls out the word. Findw finds if a word matches in the first value. If not the returned value is 0 so we add the word to the Result list. Catx places a comma between the words.

[Ksharp]

data have;
  input Animal $ Days :$10. Days_expected :$10.;
cards;
100            1,2,3,4         1,2,3,4,5
101            2,3,5            1,2,3,4,5
102            1,3,4,5         1,2,3,4,5
;
data want;
 set have;
 Days_missing=prxchange(cats('s/\b(',translate(Days,'|',','),')\b//'),-1,Days_expected);
 Days_missing=prxchange('s/^,+|,+$//',-1,strip(Days_missing));
 Days_missing=prxchange('s/,+/,/',-1,Days_missing);
run;