← SASnRCreate a macro variable to store list of values and use it in open code

Introduction

Many programs need to filter by a list of values rather than a single one — an IN-list of ages, a set of visit numbers, a handful of preferred terms.
The pattern extends the single-value case: define the list once, reference it in the filter clause.
SAS stores the list as a macro variable with %let, using %str() to protect commas from the macro processor.
R stores the list as an ordinary vector (c(59, 72)) and uses the %in% operator to test membership in either tidyverse or base dialects.
No macro quoting is needed in R because there is no macro processor to route characters through — a vector is just a vector.
This lesson filters an ADSL sample to rows whose age is 59 or 72, showing the same pattern in each language.

Create a macro variable to store list of values and use it in open code

SAS (Base SAS)+

*==============================================================================;
*Macro variable to store a list of values;
*==============================================================================;

data adsl;
    input usubjid $ trtp $ age sex $;
    datalines;
SUBJ001 Placebo 67 M
SUBJ002 DrugA   59 F
SUBJ003 Placebo 72 F
SUBJ004 DrugB   65 M
SUBJ005 Placebo 60 F
;
run;

%let age_filter = %str(59,72);

data adsl_filtered;
    set adsl;
    if age in (&age_filter.);
run;

To store a list of values in a SAS macro variable, we use %let with %str() to protect the commas from being interpreted as parameters.
%let age_filter = %str(59,72); creates a macro variable whose resolved value is the literal text "59,72".
We need %str() because bare commas in macro parameters have meaning to the macro processor — wrapping them in %str() tells SAS to treat them as ordinary characters.
In the DATA step, if age in (&age_filter.); resolves to if age in (59,72);.
Note we are not using quotes here because age is numeric — for a character list we would need to build "A","B" and use %bquote or careful quoting.
This pattern is the SAS idiom for a parameterised IN-list: change the macro, rerun the step.
After running, we check adsl_filtered and confirm only the rows with age 59 or 72 appear.

R (tidyverse)+

#==============================================================================;
#List of values in macro variable;
#==============================================================================;
library (tidyverse)

adsl <- tribble(
  ~usubjid, ~trt01p,     ~age, ~sex,
  "SUBJ001", "Placebo", 67,   "M",
  "SUBJ002", "DrugA",    59,   "F",
  "SUBJ003", "Placebo", 72,   "F",
  "SUBJ004", "DrugB",    65,   "M",
  "SUBJ005", "Placebo", 60,   "F"
)

age_filter <- c(59,72)

adsl_filtered <- adsl %>% 
  filter(age %in% age_filter)

In R, a list of values is a plain vector — no macro quoting needed.
We build the filter values with age_filter <- c(59, 72). For character values, we would use c("A", "B") with regular quotes.
Inside filter(), we use the %in% operator to test group membership: filter(age %in% age_filter).
%in% returns TRUE for each row whose age appears anywhere in age_filter, FALSE otherwise.
No special quoting is needed because R does not have a macro processor to route characters through — a vector is just a vector.
Scaling up is one line: to filter by three ages, we extend the vector to c(59, 72, 85) and the filter clause stays the same.
After running, we confirm adsl_filtered contains only rows with the listed ages.

Happy learning!

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Introduction

Create a macro variable to store list of values and use it in open code