Automate check for number of distinct values SAS - sas

Question

Looking to automate some checks and print some warnings to a log file. I think I've gotten the general idea but I'm having problems generalising the checks.
For example, I have two datasets my_data1 and my_data2. I wish to print a warning if nobs_my_data2 < nobs_my_data1. Additionally, I wish to print a warning if the number of distinct values of the variable n in my_data2 is less than 11.
Some dummy data and an attempt of the first check:
%LET N = 1000;
DATA my_data1(keep = i u x n);
a = -1;
b = 1;
max = 10;
do i = 1 to &N - 100;
u = rand("Uniform"); /* decimal values in (0,1) */
x = a + (b-a) * u; /* decimal values in (a,b) */
n = floor((1 + max) * u); /* integer values in 0..max */
OUTPUT;
END;
RUN;
DATA my_data2(keep = i u x n);
a = -1;
b = 1;
max = 10;
do i = 1 to &N;
u = rand("Uniform"); /* decimal values in (0,1) */
x = a + (b-a) * u; /* decimal values in (a,b) */
n = floor((1 + max) * u); /* integer values in 0..max */
OUTPUT;
END;
RUN;
DATA _NULL_;
FILE "\\filepath\log.txt" MOD;
SET my_data1 NOBS = NOBS1 my_data2 NOBS = NOBS2 END = END;
IF END = 1 THEN DO;
PUT "HERE'S A HEADER LINE";
END;
IF NOBS1 > NOBS2 AND END = 1 THEN DO;
PUT "WARNING!";
END;
IF END = 1 THEN DO;
PUT "HERE'S A FOOTER LINE";
END;
RUN;
How can I set up the check for the number of distinct values of n in my_data2?

Answer 1

A proc sql way to do it -
%macro nobsprint(tab1,tab2);
options nonotes; *suppresses all notes;
proc sql;
select count(*) into:nobs&tab1. from &tab1.;
select count(*) into:nobs&tab2. from &tab2.;
select count(distinct n) into:distn&tab2. from &tab2.;
quit;
%if &&nobs&tab2. < &&nobs&tab1. %then %put |WARNING! &tab2. has less recs than &tab1.|;
%if &&distn&tab2. < 11 %then %put |WARNING! distinct VAR n count in &tab2. less than 11|;
options notes; *overrides the previous option;
%mend nobsprint;
%nobsprint(my_data1,my_data2);
This would break if you have to specify libnames with the datasets due to the .. And, you can use proc printto log to print it to a file.
For your other part as to just print the %put use the above as a call -
filename mylog temp;
proc printto log=mylog; run;
options nomprint nomlogic;
%nobsprint(my_data1,my_data2);
proc printto; run;
This won't print any erroneous text to SAS log other than your custom warnings.

Answer 2

#samkart provided perhaps the most direct, easily understood way to compare the obs counts. Another consideration is performance. You can get them without reading the entire data set if your data set has millions of obs.
One method is to use nobs= option in the set statement like you did in your code, but you unnecessarily read the data sets. The following will get the counts and compare them without reading all of the observations.
62 data _null_;
63 if nobs1 ne nobs2 then putlog 'WARNING: Obs counts do not match.';
64 stop;
65 set sashelp.cars nobs=nobs1;
66 set sashelp.class nobs=nobs2;
67 run;
WARNING: Obs counts do not match.
Another option is to get the counts from sashelp.vtable or dictionary.tables. Note that you can only query dictionary.tables with proc sql.