topic Re: prxmatch in SAS Programming

prxmatch

Ronein — Tue, 16 Mar 2021 06:55:47 GMT

Hello

I would like to ask 2 questions please:

Question 1:

prxmatch('/ttt\d{8}/i',MEMNAME)

What does it mean ?

As I see it tells to take data sets names that have the word "ttt"?

What does it mean d{8}/i'???

Question 2:

input("&start",DDMMYY8.) <= input(compress(MEMNAME,,'a'),DDMMYY8.) <= input("&end",MMDDYY8.);

As I understand the date in data set name should be between start and end.

What does it mean input(compress(MEMNAME,,'a'),DDMMYY8.)??

I understand that input (......,DDMMYY8.) convert char to SAS date.

compress deleting spaces, what 'a' is doing?

Is it removing all upper and lower case characters from String (and only numbers left)?

thank you

and prxmatch('/ttt\d{8}/i',MEMNAME)
and input("&start",DDMMYY8.) <= input(compress(MEMNAME,,'a'),DDMMYY8.) <= input("&end",MMDDYY8.);

data ttt01032021;
input x y;
cards;
1 10
;
run;

data ttt02032021;
input x y;
cards;
2 11
;
run;

data ttt03032021;
input x y;
cards;
5 18
;
run;

data ttt06032021;
input x y;
cards;
6 16
;
run;


data ttt08032021;
input x y;
cards;
7 19
;
run;

%let start=01032021;
%let end=06032021;

proc sql noprint;
select MEMNAME into :ds separated by ' '
from dictionary.tables
where LIBNAME = 'WORK' 
and prxmatch('/ttt\d{8}/i',MEMNAME) 
and input("&start",DDMMYY8.) <= input(compress(MEMNAME,,'a'),DDMMYY8.) <= input("&end",MMDDYY8.);
quit;
%put &ds;

Re: prxmatch

Kurt_Bremser — Tue, 16 Mar 2021 08:14:21 GMT

As always, make use of the documentation:

PRXMATCH Function (from there, go to Tables of Perl Regular Expression (PRX) Metacharacters)

-> you will see that \d{8} searches for 8 consecutive digits, and /i means "case insensitive"

COMPRESS Function (the modifier "a")

Re: prxmatch

Ronein — Wed, 17 Mar 2021 05:26:23 GMT

Thank you,
I still dont understand what is this condition : prxmatch('/ttt\d{8}/i',MEMNAME)
I expect that when there is condition then we should have equal sign "=" and here there is no equal sign.
May you please write in words what is the meaning of this condition :prxmatch('/ttt\d{8}/i',MEMNAME)

Re: prxmatch

Ronein — Wed, 17 Mar 2021 05:35:24 GMT

So probably prxmatch('/ttt\d{8}/i',MEMNAME) is equivalent to prxmatch('/ttt\d{8}/i',MEMNAME) =1 ??

Why is it like that??

How SAS guess that prxmatch('/ttt\d{8}/i',MEMNAME) is =1??

Re: prxmatch

Kurt_Bremser — Wed, 17 Mar 2021 07:40:25 GMT

You really, really, really need to start studying the documentation. It's all in there:

PRXMATCH Function

Searches for a pattern match and returns the position at which the pattern is found.

To illustrate this, run a short example (Maxim 4):

data test;
input memname $32.;
pmatch = prxmatch('/ttt\d{8}/i',MEMNAME);
datalines;
xxx
ttt
ttt20210315
TTT20210315
ttt202103159
xxxttt20210315
;

You can see the returned positions.

Since SAS considers any numeric value not in (.,0) as true, the function can be used as the sole argument to a condition.

Re: prxmatch

japelin — Wed, 17 Mar 2021 08:18:12 GMT

It's not that you don't understand prxmatch, it's just that you don't understand that the notation 'and prxmatch('/ttt\d{8}/i',MEMNAME)' is a condition.

prxmatch('/ttt\d{8}/i',MEMNAME) equal

prxmatch('/ttt\d{8}/i',MEMNAME) not in (. 0).

both of them is the same.