Simple Macro [1-5]

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Text Substitution

You can substitute text in your program using SAS macro variables.

Example

Copy and run the SUBSCRB data set from the yellow box below. 

Data Subscrb; Input SID $ StartDate EndDate duration; Format StartDate EndDate yymmdd10.; Datalines; S100101 20330 20403 73 S100102 20204 20225 21 S100103 20270 20306 36 S100104 20364 20392 28 S100105 20382 20390 8 S100106 20440 20466 26 S100107 20099 20136 37 S100108 20182 20269 87 S100109 20110 20126 16 S100110 20297 20302 5 S100111 20195 20217 22 S100112 20222 20224 2 S100113 20240 20260 20 S100114 20378 20427 49 S100115 20323 20333 10 S100116 20318 20346 28 S100117 20173 20214 41 S100118 20157 20204 47 S100119 20140 20202 62 S100120 20419 20425 6 S100121 20437 20445 8 S100122 20445 20531 86 S100123 20432 20513 81 S100124 20216 20277 61 S100125 20413 20434 21 S100126 20201 20213 12 S100127 20448 20487 39 S100128 20354 20399 45 S100129 20156 20164 8 S100130 20394 20468 74 S100131 20124 20166 42 S100132 20307 20395 88 S100133 20271 20342 71 S100134 20259 20298 39 S100135 20221 20299 78 S100136 20195 20201 6 S100137 20236 20273 37 S100138 20353 20391 38 S100139 20187 20248 61 S100140 20135 20192 57 S100141 20379 20467 88 S100142 20402 20434 32 S100143 20313 20324 11 S100144 20101 20168 67 S100145 20267 20287 20 S100146 20418 20479 61 S100147 20152 20185 33 S100148 20145 20167 22 S100149 20306 20322 16 S100150 20302 20352 50 S100151 20253 20304 51 S100152 20275 20349 74 S100153 20294 20335 41 S100154 20162 20226 64 S100155 20190 20239 49 S100156 20203 20257 54 S100157 20149 20192 43 S100158 20096 20172 76 S100159 20232 20290 58 S100160 20442 20494 52 S100161 20278 20324 46 S100162 20366 20428 62 S100163 20252 20339 87 S100164 20426 20476 50 S100165 20322 20381 59 S100166 20383 20416 33 S100167 20338 20379 41 S100168 20190 20229 39 S100169 20162 20237 75 S100170 20346 20425 79 S100171 20361 20380 19 S100172 20399 20484 85 S100173 20143 20225 82 S100174 20358 20365 7 S100175 20310 20341 31 S100176 20137 20187 50 S100177 20103 20119 16 S100178 20290 20372 82 S100179 20410 20495 85 S100180 20294 20337 43 S100181 20103 20163 60 S100182 20185 20219 34 S100183 20300 20338 38 S100184 20163 20214 51 S100185 20131 20162 31 S100186 20299 20335 36 S100187 20267 20327 60 S100188 20156 20173 17 S100189 20286 20319 33 S100190 20351 20427 76 S100191 20408 20488 80 S100192 20292 20359 67 S100193 20340 20344 4 S100194 20310 20312 2 S100195 20131 20134 3 S100196 20239 20249 10 S100197 20307 20322 15 S100198 20450 20476 26 S100199 20256 20301 45 S100200 20401 20469 68 ; Run;

The SUBSCRB data set contains a list of gym members with the following variables:

• SID: Subscribers ID
• StartDate: the start date of the gym membership
• EndDate: the end date of the gym membership
• Duration: the length of the membership in day(s)

Now, a manager of the gym wants to get in touch with those who cancelled their membership within 10 days of signing up.

You have written the following program to print the list of members who dropped out early:

title "Subscribers who dropped out in less than 10 days";

proc print data=subscrb;
where duration < 10;
run;

The program prints the list of subscribers whose length of membership is less than 10 days. 

It also has the title that describes this list of subscribers.

Now, what if you want to print the subscribers whose duration is less than 20 days?

You just have to write the exact same program but with the new duration:

title "Subscribers who dropped out in less than 20 days";

proc print data=subscrb;
where duration < 20;
run;

This definitely does the job.

However, if you want to reuse the program a few more times, changing the duration in different parts of the program could become tedious. 

It is difficult to debug the program and easy to make a mistake.

A better way to create a reusable program is to use the SAS macro variable instead:

%let dur = 20;

title "Subscribers who dropped out in less than &dur days";

proc print data=subscrb;
where duration < &dur;
run;

The SAS macro variable (dur) was assigned the value of 20.

​It is then inserted into your program where the macro variable was referenced (&dur):

When the program is executed, the macro variable reference (&dur) will be replaced by the macro variable value (i.e. 20).

This will be the same as executing the following program instead:

Substituting text with macro variables is fairly easy.

In the next few sessions, you will learn a few more examples of how macro variables can make your program more dynamic and reusable.

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Exercise

Reuse the program above and print the list of subscribers whose length of membership is less than 30 days.

Next

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Need some help? 

Get Hint

HINT:
You can assign a different value to the macro variable at the top of the program and keep the rest of the program intact.

Get Solution

SOLUTION:
%let dur = 30;

​​title "Subscribers who dropped out in less than &dur days";

proc print data=subscrb;
where duration < &dur;
run;

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