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RegEx Question in Python

Posted on 2004-08-11
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Last Modified: 2010-04-16
Hi all,

I am beginning to dabble in some Python. I am trying to connect to a database so that I can build a table and then populate that table. Once I get this working then it will become a cron script. The purpose for this is to build citeria for searches against a database.

At any rate, here is my script so far:

                row = cursor.fetchone()
                if row==None:
                        break
                row = str(row)
                p = re.compile('[,()\']')
                row = p.sub('',row)
                p = re.compile('(PDB_[0-9])')

Now this is inside of a loop that is returning the names of databases from a query.  The database name takes the form of PDB_nnnnn(c), that's five numbers and an optional character. As you can see, I am trying to match on this pattern ( re.compile('(PDB_[0-9])') ) and this does work, except there are intermediate database files with stuff like _old, _tmp and such on the end of the PDB_nnnnn.

My question is how can I modify the re.compile('(PDB_[0-9])') to filter out those database names that have the _xxx on the end of them?

By the way, I am going against MySQL and to get all the databases I am issuing the query "SHOW DATABASES".


Thanks for your help

Paul
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Question by:PaulS_III
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Expert Comment

by:rjkimble
ID: 11774806
To match the strings you describe, try this expression:

re.compile( '^PDB_\d{5}.?$' )

The ^ matches the start of the string, the \d matches any digit, the {5} modifies the \d to match exactly 5 digits, the .? matches any character 0 or 1 times, and the $ matches the end of the string.
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Accepted Solution

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rjkimble earned 1000 total points
ID: 11775969
I overlooked one thing in my earlier post. It's better to use raw strings to define regular expresson patterns. My expression should be this instead:

re.compile( r'^PDB_\d{5}.?$' )
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Author Comment

by:PaulS_III
ID: 11782588
rj,
Absolutely perfect. Thank you so much for your input.
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Expert Comment

by:rjkimble
ID: 11784949
You're welcome -- glad to help.

.... Bob
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