How to replace part of variable values?

[wernie]

I'm trying to replace only part of a value for one variable, so it matches to merge with another dataset based on this Facility ID. Don't worry about the contaminant or value variables, I just left them in there for the example. So, I want to be able to change the facility name from WP001574 to WP531574, from WP001575 to WP531575, and so on. I just need to replace part of the value. How can I do this? Thanks!

Have:

data contam;
    input FacilityID FacilityName $ Contaminant $ Value;
    datalines;
            1           WP001574         a           5
            2           WP001575         d           10
            3           WP001576      b           2
            4           WP002475      c           8
            5           WP002476      e           30
            6           WP003843         a           2
            7           WP003843              a           5
            8           WP003844           b           8
            9           WP003845           c           20
            10         WP003846           d           30
            11        WP003847          e           55
;
run;

Want:

data contam;
    input FacilityID FacilityName $ Contaminant $ Value;
    datalines;
            1           WP531574         a           5
            2           WP531575         d           10
            3           WP531576      b           2
            4           WP532475      c           8
            5           WP532476      e           30
            6           WP533843         a           2
            7           WP533843              a           5
            8           WP533844           b           8
            9           WP533845           c           20
            10         WP533846           d           30
            11        WP533847          e           55
;
run;

[Astounding · Accepted solution]

The SUBSTR function permits this:

substr(facilityName, 3, 2) = '35';

[data_null__]

RTM: Function TRANSTRN
http://support.sas.com/documentation/cdl/en/lefunctionsref/69762/HTML/default/viewer.htm#n101a8jch5t...

Or for this specific job SUBSTR(left of 😃

http://support.sas.com/documentation/cdl/en/lefunctionsref/69762/HTML/default/viewer.htm#p0uev77ebdw...