suggests words when entering letters of coincidence

from kivy.app import App
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.dropdown import DropDown
from kivy.uix.button import Button
from kivy.uix.textinput import TextInput
from kivy.properties import ListProperty, StringProperty
from kivy.clock import Clock

import re

from kivy.lang import Builder

Builder.load_string('''
<MainView>:
    ComboEdit:
        size_hint: .5, .3
        pos_hint: {'center':(.5, .5)}
        # `args` is the keyword for arguments passed to `on_text` in kv language
        on_text: root.on_text(self, args[1])


''')

class ComboEdit(TextInput):
    '''
    This class defines a Editable Combo-Box in the traditional sense
    that shows it's options
    '''

    options = ListProperty(('', ))
    '''
    :data:`options` defines the list of options that will be displayed when
    touch is released from this widget.
    '''

    def __init__(self, **kw):
        ddn = self.drop_down = DropDown()
        ddn.bind(on_select=self.on_select)
        super(ComboEdit, self).__init__(**kw)

    def on_options(self, instance, value):

        ddn = self.drop_down
        # clear old options
        ddn.clear_widgets()
        for option in value:
            # create a button for each option
            but = Button(text=option,
                        size_hint_y=None,
                        height='36sp',
                        # and make sure the press of the button calls select
                        # will results in calling `self.on_select`
                        on_release=lambda btn: ddn.select(btn.text))
            ddn.add_widget(but)

    def on_select(self, instance, value):
        # on selection of Drop down Item... do what you want here
        # update text of selection to the edit box

        self.text = value

class MainView(FloatLayout):

    rtsstr = StringProperty("".join(("Substrate1,,,Substrate1,,,Substrate1,,,",
                            "Substrate1,,,Substrate1,,,Substrate_coating",
                            ",,,silicon,,,silicon_Substrate,,,substrate_",
                            "silicon,,,")))
    #print(rtsstr)
    def on_text(self, instance, value):
        print(instance, value)
        #instance.drop_down.dismiss()
        if value == '':
            instance.options=[]
        else:
            match = re.findall("(?<=,{3})(?:(?!,{3}).)*?%s.*?(?=,{3})" % value,\
                                self.rtsstr, re.IGNORECASE)
            #using a set to remove duplicates, if any.
            instance.options = list(set(match))


        instance.drop_down.open(instance)


class TestApp(App):

    def build(self):
        return MainView()

if __name__ == '__main__':
    TestApp().run()