list2format Macro

Difficulty Level

Beginner

Published on : 18/03/2022

This SAS^© macro, named `list2format`, dynamically generates a SAS^© numeric format. It accepts two parameters: `fmtname` to specify the name of the format to create, and `list` for a character string containing a comma-separated list of values, ideally enclosed in parentheses (e.g., `(ALT,BILI,CREAT)`). The macro parses this list, extracts each element, and sequentially associates it with an integer in the format definition via `PROC FORMAT`. Each element in the list is cleaned of superfluous spaces using `%sysfunc(strip())` before being integrated into the format. It is a practical tool for converting a list of strings into a usable numeric format for categorical variables.

Data Analysis

Type : CREATION_INTERNE

The data used for format creation comes from a list of values passed as a parameter to the macro and processed internally, without external dependencies or SASHELP data.

1 Code Block

MACRO / PROC FORMAT Data

Explanation :
This block defines the `list2format` macro. It initializes local variables `i` (counter) and `item` to iterate over the list of values provided in the `&list` parameter. The `%qscan` function is used with `%nrbquote` to extract each element from the list, taking into account the specified delimiters (comma and parentheses). Each extracted element is stored in a dynamic macro variable (`list_&i`). Once the list is fully traversed, `list_n` contains the total number of elements. Then, a `PROC FORMAT` block is generated. A `%do` loop is used to create number=value associations in the format definition. For each iteration, the number (`&i`) is associated with the corresponding list value (referenced by `&&list_&i`) after being cleaned of spaces with `%sysfunc(strip())`. The final `run;` executes the formatting procedure.

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1	/--------------------------------------------------------------------------------------
2	Copyright 2017, Rho, Inc. All rights reserved.
3
4	PROGRAM: list2format
5
6	PURPOSE: Create a numeric format based on a list of values.
7
8	INPUT: fmtname= format name
9	list= list of values
10
11	DETAILS:
12	- list should be specified as comma-separated values enclosed in parentheses.
13	e.g., list=(ALT,BILI,CREAT).
14
15	PROGRAM HISTORY:
16	DATE PROGRAMMER DESCRIPTION
17	--------- --------------- ------------------------------------------------------
18	2017-12-15 Shane Rosanbalm Create.
19
20	--------------------------------------------------------------------------------------/
21
22	%macro list2format
23	(fmtname=
24	,list=
25	);
26
27	%*--- get first item ---;
28	%local i item;
29	%let i = 1;
30	%let item = %qscan(%nrbquote(&list),&i,%str((),));
31
32	%*--- continue IF more items ---;
33	%DO %while(&item ne );
34	%local list_&i;
35	%let list_&i = &item;
36	%let i = %eval(&i+1);
37	%let item = %qscan(%nrbquote(&list),&i,%str((),));
38	%END;
39
40	%*--- number of items found ---;
41	%local list_n;
42	%let list_n = %eval(&i-1);
43
44	%*--- make a FORMAT ---;
45	PROC FORMAT;
46	value &fmtname
47	%DO i = 1 %to &list_n;
48	&i = "%sysfunc(strip(&&list_&i))"
49	%END;
50	;
51	RUN;
52
53	%mend list2format;

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Difficulty Level

Published on : 18/03/2022

Data Analysis

1 Code Block

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