topic Re: how to use Regular expression read strings on multiple lines in SAS Programming

how to use Regular expression read strings on multiple lines

gyambqt — Thu, 07 May 2015 04:40:13 GMT

Hello experts,

Can someone tell me why the metacharacter \n is not working for the program belw

data a;
infile cards truncover;
length a $1;
input a $150.;
cards;
a
b
run;

data b;
set a;

e=prxmatch("/a\nb",a);
run;

Thanks

Re: how to use Regular expression read strings on multiple lines

Ksharp — Thu, 07 May 2015 12:07:39 GMT

You have two obs not one , therefore PRX can't work on that situation .

Re: how to use Regular expression read strings on multiple lines

Loko — Thu, 07 May 2015 12:16:52 GMT

Hello,

Maybe this is what you are looking for:

data a;
a="103 Pennsylvania Ave. NW,";output;
a="Washington, DC 20216" ;output;
a="NY, DC 20216" ;output;
run;

data b;
set a;
b=prxparse("/103 Pennsylvania Ave\. NW|Washington, DC 20216/");
e= prxmatch(b,a);

run;

Check also the following link:

http://support.sas.com/documentation/cdl/en/lrdict/64316/HTML/default/viewer.htm#a002295977.htm

Re: how to use Regular expression read strings on multiple lines

gyambqt — Thu, 07 May 2015 20:55:53 GMT

HI ksharp,

can an you use \n to read new line in regular expression?

Re: how to use Regular expression read strings on multiple lines

gyambqt — Fri, 08 May 2015 01:37:29 GMT

I have modified the program to make it more simple.

Re: how to use Regular expression read strings on multiple lines

Tom — Fri, 08 May 2015 03:12:11 GMT

No.

If you have organized your dataset so that each line is on a separate observation you cannot use the SAS perl regular expression functions to operate across observations.

To check if you ever have the condition that "B" follows "A" in your data set perhaps you want to use LAG() function?

Here is a trivial example .

data want ;

input a $ ;

if a='B' and lag(a)='A' then found=1;

else found=0;

CARDS;

run;

In this case only the second and the final observation will have FOUND set to 1.

Re: how to use Regular expression read strings on multiple lines

Peter_L — Tue, 12 May 2015 10:48:01 GMT

I would not use SAS for this type of parsing of a structured text file. Use awk: it is designed for this. Awk is a small program available on almost all operating systems. It is part of unix. If you do not have awk, use perl, which is bigger and more complex. After you have used awk to reorganise the data, read it into SAS. You should be able to run the awk from SAS, or use a command script to run both. I use this method frequently.