Document Identifier

The Document Identifier package has one public function 'Identify'. It looks through a passed module and attempts to construct objects from the remaining passed arguments.

Basic Use

>>> import document_identifier as di
>>> import document_identifier.RealID as RealID
>>> unknown_document = {'raw_input': "   -\x1eQ\x01%PAGETTYSBURG^SMITH$JOHN^11 WINDERMERE ST$^?                                                                  ;63632208065640=160819340807=?"}
>>> documents = di.Identify(scope=RealID, **unknown_document)  # return all constructable machine readable travel documents.
>>> print "\n".join(map(str, documents))

Advanced Use

Identify's Keywords

scope

scope is either a collection of callable's (class constructors), or a module object with an public __all__ collection of classes.

return_single

return_single is a Boolean flag to specify the return type. It defaults to false. When true, Identify returns the first constructable object found. When false it returns a list of all constructable object found.

kwargs

Identify takes all remaining arguments and passes them to scope's callables. The sub-modules provided with this package, (MRTD, RealID, etc), all take a generic raw_input parameter which is then rearranged by each class into what it needs.

Creating a module

The Document Identifier package has a DocumentBase class which defines the __init__ and a basic __str__ methods. It also has a class level Format dictionary.

• __init__ should be overridden to convert the DocumentBase.__init__ class attributes into the proper format.
• Format should be overridden to require the proper passed arguments.

Basic Structure

Format is a dictionary of RE module regular expression objects. Any key present in Format will be required by DocumentBase.__init__.

It is __init__'s job to match the passed arguments with Formats values, and create object attributes from the captured regex groups.

The captured groups will be of type string, and may need reformatting in any derived classes.

Identifying a Barcode

For this example we will create our own module that identifies UPC-A style barcodes.

Lets create a file and import the basics.:

import re
from document_identifier import DocumentBase

__all__ = ["UPC_A"]

Now lets create a Document that matches and captures only 12 digits.:

class UPC_A(DocumentBase):
  Format = {
    'raw_input': re.compile(r'^(?P<number>\d{12})$'),
  }

UPC-A barcodes have a check digit so let add that logic to the constructor.:

def __init__(self, **kwargs):
    super(UPC_A, self).__init__(**kwargs)
    product = 0
    for num, mul in zip(map(int, self.number[:-1]), [3,1]*6):
        product += num * mul
    product = 10 - (product % 10)

    if product != int(self.number[-1])):
        raise ValueError("Invalid check digit")

For a more extensive abuse of inheritance check out the MRTD (Machine Readable Travel Document) module.