Syntax Reference#

A reference for the Data Step statements supported by limulus.
For differences from SAS language, see Differences from SAS language. For Column-Oriented API and Ssession-level helpers such as sort, sql and include, see API Reference and Changelog.

DATA Statement#

data <output1> [<output2> ...];
  ...
run;

Specifying multiple output destinations creates a multi-output DATA step.
Using an explicit output statement allows row-level routing.

SET Statement#

set <dataset> [<dataset2> ...] [end=<var>] [indsname=<var>];

Option	Description
`end=last`	Defines a variable that becomes `1` at the last row
`indsname=src`	Stores the current dataset name in a variable

Listing multiple datasets performs a vertical concatenation.

Interleaving with BY#

set <dataset1> <dataset2> ...;
by <key>;

When by is specified together with multiple datasets, rows from all sources are merge-sorted by the BY key rather than concatenated in source order. This matches “interleaving” semantics.

data combined;
  set sales2023 sales2024;
  by date;
run;

MERGE Statement#

merge <dataset>(in=<var>) [<dataset2>(in=<var>)];
by <key>;

The in= variable is 1 when a row exists in the source table, 0 otherwise.
If by is not specified, just concat.
If duplicate column names exist, an error is raised instead of overwriting.

WHERE Statement#

where <condition>;

Placed after SET/MERGE. Applies a filter at data read time.

Subsetting IF Statement#

if <condition>;

Applies a filter after data is read.

IF / ELSE IF / ELSE Statement#

if <condition> then <statement>;
else if <condition> then <statement>;
else <statement>;

Use DO...END to group multiple statements:

if x > 0 then do;
  y = x * 2;
  z = 1;
end;

DO / END Statement#

do <var> = <start> to <stop> [by <step>];
  ...
end;

Used for counter loops as well as conditional blocks (if...then do;).

BY Statement#

by <var> [<var2> ...];

Used in combination with SET/MERGE.
Makes FIRST.<var> / LAST.<var> automatic variables available.

OUTPUT Statement#

output [<dataset>];

Without arguments, writes to all output destinations.
With an argument, writes only to the specified dataset.

STOP Statement#

stop ;

Stops the Data Step processing.

KEEP / DROP Statement#

keep <var1> [<var2> ...];
drop <var1> [<var2> ...];

Specifies variables to include in / exclude from the output dataset.

RENAME Statement#

rename <oldname>=<newname> [<oldname>=<newname> ...];

RETAIN Statement#

retain <var> [<initial>] [<var2> [<initial2>] ...];

Retains the value of a variable across iterations. If the initial value is omitted, defaults to null.

ARRAY Statement#

array <name> <var1> [<var2> ...];

Assigns a name to a group of variables. Index access (name[1]) is supported.

SUM Statement (Cumulative Addition)#

<var> + <expression>;

Performs cumulative addition without RETAIN.

ASSIGN Statement (Assignment)#

<varname> = <expression>;

DELETE Statement#

delete;

Does not output the current row (moves to the next iteration of the PDV loop).

Built-in Functions#

String#

Function	Description	Example
`substr(s, pos, len)`	Substring	`substr(name, 1, 3)`
`upcase(s)`	Convert to uppercase	`upcase(sex)`
`lowcase(s)`	Convert to lowercase	`lowcase(name)`
`propcase(s)`	Capitalize first letter	`propcase(city)`
`trim(s)`	Remove trailing spaces	`trim(raw_name)`
`strip(s)`	Remove leading and trailing spaces	`strip(raw_name)`
`length(s)`	String length	`length(name)`
`lengthn(s)`	NULL-safe string length	`lengthn(comment)`
`reverse(s)`	Reverse string	`reverse(code)`
`scan(s, n, dlm)`	n-th token	`scan(path, 2, '/')`
`compress(s, chars)`	Remove specified characters	`compress(phone, '-')`
`index(s, sub)`	Position of substring	`index(name, 'AL')`
`find(s, sub)`	Position of substring	`find(name, 'al', 1, 'i')`
`tranwrd(s, from, to)`	Word replacement	`tranwrd(note, 'old', 'new')`
`translate(s, to, from)`	Character translation	`translate(code, 'AB', '12')`
`countw(s, dlm)`	Word count	`countw(text, ' ')`
`cat(a, b, ...)`	Concatenate	`cat(first, last)`
`cats(a, b, ...)`	Concatenate with trim	`cats(first, last)`
`catt(a, b, ...)`	Concatenate with trailing trim	`catt(first, last)`
`catx(dlm, a, b, ...)`	Concatenate with delimiter	`catx('-', y, m, d)`
`repeat(s, n)`	Repeat n times	`repeat('*', 3)`

Numeric#

Function	Description	Example
`abs(x)`	Absolute value	`abs(delta)`
`round(x, n)`	Round (0.5 rounds away from zero)	`round(bmi, 0.1)`
`ceil(x)`	Ceiling	`ceil(value)`
`floor(x)`	Floor	`floor(value)`
`int(x)`	Integer part	`int(score)`
`mod(x, y)`	Remainder	`mod(id, 2)`
`max(a, b, ...)`	Maximum	`max(v1, v2, v3)`
`min(a, b, ...)`	Minimum	`min(v1, v2, v3)`
`sum(a, b, ...)`	Sum	`sum(v1, v2, v3)`
`mean(a, b, ...)`	Mean	`mean(v1, v2, v3)`
`sqrt(x)`	Square root	`sqrt(var)`
`log(x)`	Natural logarithm	`log(value)`
`exp(x)`	Exponent	`exp(value)`
`sign(x)`	Sign	`sign(change)`

Missing Values / Dates#

Function	Description	Example
`missing(x)`	Returns `1` if missing	`missing(result)`
`nmiss(a, b, ...)`	Count of missing values	`nmiss(v1, v2, v3)`
`cmiss(a, b, ...)`	Count of missing values (mixed types)	`cmiss(name, age, score)`
`lag(x, n)`	Previous row’s value	`lag(amount)`
`mdy(m, d, y)`	Month/day/year to date	`mdy(1, 15, 2025)`
`year(d)`	Year from date	`year(mdy(1, 15, 2025))`
`intck(unit, from, to)`	Date difference	`intck('day', mdy(1,1,2025), mdy(1,10,2025))`

Regular Expressions#

Function	Description	Example
`prxmatch(pattern, s)`	Regex match position	`prxmatch('/abc/i', text)`
`prxchange(pattern, times, s)`	Regex substitution	`prxchange('s/ +/ /', -1, text)`

ARRAY Helpers#

Function	Description	Example
`dim(array)`	Number of elements in array	`dim(vars)`
`vname(array[i])`	Variable name of array element	`vname(vars[2])`

Custom Functions#

Function	Description	Example
`lead(x, n)`	Next row’s value	`lead(amount)`
`shift(x, n)`	negative n behaves like `lag`, positive n like `lead`	`shift(amount, -1)` `shift(amount, 1)`
`apply`	Apply a function.	`apply('double',amount)` `apply(lambda x: x*2,amount)` `apply('math.sqrt',value)`

Note: apply() is not supported by the Rust backend. When backend="auto" (the default), execution automatically falls back to the Python backend whenever apply() appears in the code. To suppress the fallback and always use the Python backend, set backend="python" on the Session.

Syntax Reference

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