Plugins

You eventually want to create your own preprocessing steps, your own features or another implementation of the same feature. You can do so by specifying a Python script in preprocessing or features.

If a preprocessing class or a feature class exists in the official hwrt and in a plugin simultaniously, the hwrt implementation is used.

Preprocessing Classes

Every feature class must have a __str__, __repr__ and a __call__ function where

• __call__ must take exactly one argument of type HandwrittenData
• __call__ must call the Handwriting.set_points

Feature Classes

Every feature class must have a __str__, __repr__, __call__ and get_dimension function where

• __call__ must take exactly one argument of type HandwrittenData
• __call__ must return a list of length get_dimension()
• get_dimension must return a positive number
• have a ‘normalize’ attribute that is either true or false

Preprocessing Plugin Example

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import hwrt.handwritten_data as HandwrittenData


class Nullify(object):
    def __repr__(self):
        return "Nullify"

    def __str__(self):
        return "Nullify"

    def __call__(self, hwr_obj):
        assert isinstance(hwr_obj, handwritten_data.HandwrittenData), \
            "handwritten data is not of type HandwrittenData, but of %r" % \
            type(hwr_obj)
        # pointlist = hwr_obj.get_pointlist()
        new_pointlist = []
        new_stroke = []
        new_stroke.append({'x': 0, 'y': 0, 'time': 0})
        new_pointlist.append(new_stroke)
        hwr_obj.set_pointlist(new_pointlist)

Feature Plugin Example

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import hwrt.handwritten_data as HandwrittenData


class StrokeCountTata(object):

    """Stroke count as a 1 dimensional recording."""

    normalize = True

    def __repr__(self):
        return "StrokeCount"

    def __str__(self):
        return "stroke count"

    def get_dimension(self):
        return 1

    def __call__(self, hwr_obj):
        assert isinstance(hwr_obj, handwritten_data.HandwrittenData), \
            "handwritten data is not of type HandwrittenData, but of %r" % \
            type(hwr_obj)
        return [len(hwr_obj.get_pointlist())]