title: How to change text of a label in the kivy language with python
body: <p>I was wondering how I could change the text of a label made inside the Kivy language using Python.
  Like how would I have user input from python be made as the text of a label in kivy.
  (By the way I have the formatting correct in the actual program but I screwed up pasting it to stackoverflow)
  Say if I wanted to make the text of the label in  from the code be a random number generated in python how would I go about doing that?</p>
  
  <pre><code>from kivy.app import App
  from kivy.lang import Builder
  from kivy.uix.screenmanager import ScreenManager, Screen
  from kivy.graphics import Color, Rectangle
  from kivy.properties import ObjectProperty
  
  # Create both screens. Please note the root.manager.current: this is how
  # you can control the ScreenManager from kv. Each screen has by default a
  # property manager that gives you the instance of the ScreenManager used.
  
  
  Builder.load_string("""
  &lt;ButImage@ButtonBehavior+AsyncImage&gt;
  &lt;TutImage@ButtonBehavior+AsyncImage&gt;
  &lt;MenuScreen&gt;:
  GridLayout:
      cols: 4
      row_force_default: True
      col_default_width: 175
      row_default_height: 150
      padding: 15
      spacing: 15
      canvas.before:
          BorderImage:
              # BorderImage behaves like the CSS BorderImage
              border: 10, 10, 10, 10
              source: '/Users/clayhigh/Desktop/kivy/aot.png'
              pos: self.pos
              size: self.size
      Button:
          text: 'Goto settings'
          background_color: 1,0,0,0.5
          on_press: root.manager.current = 'settings'
      ButImage:
          on_press: root.manager.current = 'UBW'
          id: but
          size_hint: .5, .5
          opacity: 1 if self.state == 'normal' else .5
          allow_stretch: True
          keep_ratio: False
          source: 'http://s3.amazonaws.com/rapgenius/1361742626_beautiful-ocean-beautiful-pictures-27115524-1440-900.jpg'
          Label:
              center: but.center
              text: "UBW"
              color: 0.78,0.145,0.016,2
      ButImage:
          id: lh
          size_hint: .5, .5
          opacity: 1 if self.state == 'normal' else .5
          allow_stretch: True
          keep_ratio: False
          source: 'http://s3.amazonaws.com/rapgenius/1361742626_beautiful-ocean-beautiful-pictures-27115524-1440-900.jpg'
          Label:
              center: lh.center
              text: "LH 2"
              color: 0,0,0,1
      ButImage:
          id: ttl
          size_hint: .5, .5
          opacity: 1 if self.state == 'normal' else .5
          allow_stretch: True
          keep_ratio: False
          source: 'http://s3.amazonaws.com/rapgenius/1361742626_beautiful-ocean-beautiful-pictures-27115524-1440-900.jpg'
          Label:
              center: ttl.center
              text: "TwTl"
              color: 0,0,0,1
      ButImage:
          id: gris
          size_hint: .5, .5
          opacity: 1 if self.state == 'normal' else .5
          allow_stretch: True
          keep_ratio: False
          source: 'http://s3.amazonaws.com/rapgenius/1361742626_beautiful-ocean-beautiful-pictures-27115524-1440-900.jpg'
          Label:
              center: gris.center
              text: "Gris"
              color: 0,0,0,1
      ButImage:
          id: shig
          size_hint: .5, .5
          opacity: 1 if self.state == 'normal' else .5
          allow_stretch: True
          keep_ratio: False
          source: 'http://s3.amazonaws.com/rapgenius/1361742626_beautiful-ocean-beautiful-pictures-27115524-1440-900.jpg'
          Label:
              center: shig.center
              text: "Shig"
              color: 0,0,0,1
      Button:
          text: 'Test3'
          background_color: 1,0,0,0.5
      Button:
          text: 'Test4'
          background_color: 1,0,0,0.5
      Button:
          text: 'Quit'
          background_color: 1,0,0,0.5
          on_press: App.on_stop
  
  &lt;SettingsScreen&gt;:
  GridLayout:
      row_force_default: True
      row_default_height: 100
      cols: 2
      canvas.before:
          BorderImage:
              # BorderImage behaves like the CSS BorderImage
              border: 10, 10, 10, 10
              source: '/Users/clayhigh/Desktop/kivy/ato.jpeg'
              pos: self.pos
              size: self.size
      Button:
          text: 'Button'
          color: 0,0,.5
          background_color: 1,0,0,1
      Button:
          text: 'Back to menu'
          background_color: 1,0,0,1
          on_press: root.manager.current = 'menu'
  &lt;UBW&gt;:
  GridLayout:
      row_force_default: True
      row_default_height: 100
      cols: 2
      canvas.before:
          Color:
              rgb: .5, .5, .5
          Rectangle:
              pos: self.pos
              size: self.size
          Color:
              rgb: 1, 1, 1
          BorderImage:
              # BorderImage behaves like the CSS BorderImage
              border: 10, 10, 10, 10
              source: '/Users/clayhigh/Desktop/kivy/fsn.jpg'
              pos: self.pos
              size: self.size
      Button:
          text: 'Back to menu'
          color: 0,0,.5
          on_press: root.manager.current = 'menu'
          background_color: 1,0,0,1
      Label:
          id: AName
          text: "F S/N: UBW"
          font_size: '24sp'
  """)
  
  # Declare both screens
  
  
  class MenuScreen(Screen):
  pass
  
  
  class SettingsScreen(Screen):
  pass
  
  
  class UBW(Screen):
  pass
  
  # Create the screen manager
  sm = ScreenManager()
  sm.add_widget(MenuScreen(name='menu'))
  sm.add_widget(SettingsScreen(name='settings'))
  sm.add_widget(UBW(name='UBW'))
  
  
  class TestApp(App):
  
  def build(self):
      return sm
  
  if __name__ == '__main__':
  TestApp().run()
  </code></pre>