[Python-talk] PySIG report, 27 Jan 2011

[Lloyd Kvam]

On Fri, 2011-01-28 at 20:54 -0500, Bill Sconce wrote:
> One of our membership is introducing himself to Python by discovering
> for himself how to use it to clean up a name-and-address database. 

An all too common sort of problem.  The Python re (regular expression)
module provides the sub method for making string substitutions.
        http://docs.python.org/library/re.html#re.sub
The key thing to note is that the repl parameter does not have to be a
string.  It can be a function!


I wrote a Converter class that takes in a dictionary of string
conversions.  The "old" strings are assumed to be words.  This allows
you to have  a dictionary like dict(
        i = 'I',
        in = 'Out',
        )
where some of the strings are contained in others.  I needed that for
converting field names.  The class combines all of the "old" strings
into a regular expression pattern and constructs the repl function to be
used by the pattern's sub method.

Then the call to pattern.sub is packaged using functools.partial and
named _cvt.  A separate method, convert, documents the remaining free
parameters for the sub call.  I think it makes things less mysterious.
Finally convert is assigned to __call__ so that Converter objects can be
called directly.

The last time I used this was to help my daughter with late changes for
the Ethics Bowl held last Fall at Dartmouth.  
        http://www.dartmouth.edu/~ethics/nereb/index.html
The scheduling program uses place holders for rooms and team names.  She
needed to convert the generated schedule (ethics-bowl.txt) into
something meaningful for the participants.

        <ethics-bowl.txt python fix-ethics-matches.py

did the trick.

As you can tell from the length of this email, I was pretty tickled when
I realized how nicely this kind of logic could be packaged.

-- 
Lloyd Kvam
Venix Corp
DLSLUG/GNHLUG library
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  Panel      Round One     Round Two      Round Three

-------     -------     -------      -------

    A        2 vs 6      3 vs 16      9 vs 19

    B        3 vs 17     8 vs 11      10 vs 20

    C        4 vs 9     10 vs 18      11 vs 14

    D        5 vs 10     9 vs 17      2 vs 12

    E        7 vs 11     12 vs 13     1 vs 6

    F        12 vs 15    2 vs 14      3 vs 13

    G        14 vs 16    4 vs 19      5 vs 18

    H        18 vs 19    5 vs 20      7 vs 17

    I        8 vs 20     1 vs 7       15 vs 16

    J        1 vs 13     6 vs 15      4 vs 8

Here are the new instructions for each team:

Team #          Round One          Round Two         Round Three
              Panel Opponent     Panel Opponent    Panel Opponent

------       -----  ------      -----  ------     -----  ------

   1            J--13          I--7         E--6

   2            A--6          F--14         D--12

   3            B--17          A--16         F--13

   4            C--9          G--19         J--8

   5            D--10          H--20         G--18

   6            A--2          J--15         E--1

   7            E--11          I--1         H--17

   8            I--20          B--11         J--4

   9            C--4          D--17         A--19

  10            D--5          C--18         B--20

  11            E--7          B--8         C--14

  12            F--15          E--13         D--2

  13            J--1          E--12         F--3

  14            G--16          F--2         C--11

  15            F--12          J--6         I--16

  16            G--14          A--3         I--15

  17            B--3          D--9         H--7

  18            H--19          C--10         G--5

  19            H--18          G--4         A--9

  20            I--8          H--5         B--10