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Thursday, August 21, 2008

HOW TO USE THE SCAN FUNCTION:

USING THE SCAN FUNCTION:

SCAN(string,n,delimiters): returns the nth word from the character string string, where words are delimited by the characters in delimiters. 

It is used to extract words from a  character value when the relative order of words is known, but their starting positions are not.

NewVar=SCAN(string,n<,delimiters>); -returns the nth ‘word’ in the string
 
When the SCAN function is used:
�� the length of the created variable is 200 bytes if it is not previously defined with a LENGTH statement
�� delimiters before the first word have no effect When the SCAN function is used,
�� any character or set of characters can serve as delimiters

Points to remember while using SCAN Function:
�� a missing value is returned if there are fewer than n words in string
�� two or more contiguous delimiters are treated as a single delimiter
�� if  n is negative, SCAN selects the word in the character string starting from the end of string.

�� If you omit delimiters , default is blank . < ( + & ! $ * ) ; ^ - / , %
Source: http://www.biostat.jhsph.edu/bstcourse/bio632/SummerInst/Class2/class2.pdf

Example of use:

Name= 'StudySAS, Blog';
Last= scan(Name,2,',');  *Note : Comma ',' is Delimiter here;

Results in Last returns to Blog

Using the SCAN function from SAS Functions by Example:

Suppose you want to produce an alphabetical list by last name, but your NAME variable contains FIRST, possibly a middle initial, and LAST name. The SCAN function makes quick work of this. Note that the LAST_NAME variable in PROC REPORT has the attribute of ORDER and NOPRINT, so that the list is in alphabetical order of last name but all that shows up is the original NAME variable in First, Middle, and Last name order.

DATA FIRST_LAST;
INPUT @1 NAME $20.@21 PHONE $13.;

***Extract the last name from NAME;


LAST_NAME = SCAN(NAME,-1,' '); /* Scans from the right */
DATALINES;
Jeff W. Snoker (908)782-4382
Raymond Albert (732)235-4444
Steven J. Foster (201)567-9876
Jose Romerez (516)593-2377
;

PROC REPORT DATA=FIRST_LAST NOWD;
TITLE "Names and Phone Numbers in Alphabetical Order (by Last Name)";
COLUMNS NAME PHONE LAST_NAME;
DEFINE LAST_NAME / ORDER NOPRINT WIDTH=20;
DEFINE NAME / DISPLAY 'Name' LEFT WIDTH=20;
DEFINE PHONE / DISPLAY 'Phone Number' WIDTH=13 FORMAT=$13.;
RUN;

source: www.support.sas.com

4 comments:

Kevin said...

note to the folks playing along at home -- make sure you pad the datalines in this code so that the phone number starts at column 21. it won't work right if you copy and paste it directly (like i just did...). :-P

Shan Putnam said...

Hi,

a google search for 'sas scan alphabetical' led me to your blog.

which me to ask a question regarding scan function. is there anyway for scan to return an alphabetical component listing.
e.g.,
the study is to list all cars at a specific 4-way stoplight on a multi-lane road (pure fictional exmple!)

variable is 'CARS'
data lines listed as CARS looks like this:

chevy, ford, chyrsler, alpha romeo;
toyota, mazada, studebaker, ;
ford, ford, chevy, BMW;
etc..

car1 = scan(CARS,1,",");
car2 = scan(CARS,2,",");
car3 = scan(CARS,3,",");
car4 = scan(CARS,4,",");
etc..

what I would like is the have scan do is to ensure that 'car1' always has the alphabetical first from the list of cars in the multi-listed variable CARS.

so results would look like this:

cars1 cars2 cars3 cars4
alpha romeo chevy chrysler ford
mazada studebaker toyota
BMW chevy ford ford

thanks
shan
shan8299@gmail.com

Anonymous said...

Seems like it won't work when the delimiter is more than one character?

sarath said...

Hi Shan,

I don't know how to sort the values using the SCAN function. But using the Call Sortc routine you can do this.

Here is the code.

data test;
length cars $200;
input cars $1-50;
cards;
chevy, ford, chyrsler, alpha romeo,
toyota, mazada, studebaker,
ford, ford, chevy, BMW,
;
run;


data test1;
set test;
car1 = scan(CARS,1,",");
car2 = scan(CARS,2,",");
car3 = scan(CARS,3,",");
car4 = scan(CARS,4,",");
array x(*) $ car1 car2 car3 car4;
call sortc(of x(*));
run;

Let me know if you have any questions.

Sarath

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