[vpopper]

I am converting a perl module for filtering form input into a python equivalent, and need the python equivalent of the perl 'tr' operator. I came up with some routines (below), but wondered if there was a better way?

These are the some of the perl routines:

sub squeeze_ws {
    my $str = shift;
    $str =~ tr/ / /s;
    return $str;
}

sub force_int {
    my $str = shift; 
    $str =~ tr/0-9//cd;
    return $str;
}

sub force_alpha {
    my $str = shift; 
    $str =~ tr/0-9a-zA-Z//cd;
    return $str;
}

sub force_char {
    my $str = shift; 
    $str =~ tr/a-zA-Z//cd;
    return $str;
}

And here is the python equivalent:

class Filter(object):
    def __init__(self):
        pass

    def chop_blanks(s):
        return s.strip()

    def squeeze_ws(s):
        s = s.expandtabs()
        a = s.split(' ')
        return ' '.join([i for i in a if i and not i.isspace()])

    def force_int(s):
        return Filter.trcd(s, range(0,9))

    def force_alpha(s):
        chars = "abcdefghijklmnopqrstuvwxyz" \
                "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
                "0123456789"
        return Filter.trcd(s, chars)

    def force_char(s):
        chars = "abcdefghijklmnopqrstuvwxyz" \
                "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        return Filter.trcd(s, chars)

    def trcd(s, keep):
        allchars = string.maketrans('', '')
        delchars = ''.join([c for c in allchars if c not in keep])
        return s.translate(allchars, delchars)

    chop_blanks = staticmethod(chop_blanks)
    # ...

Any thoughts?

[telex4]

Look into the re module. It should do all you need.

Also, this page is really handy if you, like me, are coming from Perl to Python:

http://starship.python.net/~da/jak/cookbook.html