Normalizing LoC Call Numbers for sorting
Updated: I missed a ‘?’ in the original code that pushed a single cutter into the second-cutter position. Fixed below.
Crap. Update 2: Initial letters can be three characters long. Regexp and output changed.
LoC Call numbers tend to be a mess, and I’ve been working this morning trying to normalize them for easy string comparison.
The perl function below takes a call number (with some level of sloppiness) and returns a string suitable for comparisons with other strings returned by the function. It outputs stuff like this:
E E 0000.0000 0000 0000 E 184 .A1 G78 E 0184.0000A 1000G 7800 E184.A2 G78 1967 E 0184.0000A 2000G 7800 1967 E184.A2 G78 1970 E 0184.0000A 2000G 7800 1970 EA EA0000.0000 0000 0000 EA 10 EA0010.0000 0000 0000 EA 10 1970 EA0010.0000 0000 0000 1970 EA10 B7 EA0010.0000B 7000 0000 EA 10.B7.G8 EA0010.0000B 7000G 8000 EA10.5 EA0010.5000 0000 0000The code, in perl, follows:
sub normalizeLC {
- my $lc = uc(shift);
- $lc =~ /^
- \s*
- ([A-Z]{1,3}) # alpha
- \s*
- ( # optional numbers
- \d+
- (?: \s*\.\s*\d+)? # …with optional decimal point
- )?
- \s*
- (?: # optional cutter
- \.? \s*
- ([A-Z]+) # cutter letter
- \s*
- (\d+)? # cutter numbers
- )?
- (?: # optional cutter
- \.? \s*
- ([A-Z]+) # cutter letter
- \s*
- (\d+)? # cutter numbers
- )?
- \s*
- (.*?) # everthing else
- \s*$
- /x;
- my ($alpha, $num, $c1alpha, $c1num, $c2alpha, $c2num, $extra) = ($1, $2, $3, $4, $5, $6, $7);
- $c1num .= 0 x (4 – length($c1num)); # Pad out to four decimal places
- $c2num .= 0 x (4 – length($c2num)); # ditto
- $extra = ' ' . $extra if ($extra);
- return sprintf("%-3s%09.4f%-2s%4s%-2s%4s%s", $alpha, $num, $c1alpha, $c1num, $c2alpha, $c2num, $extra);
- }
Tags: callnumbers code
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