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2.2. State Transition

Create a dialogue flow using state transitions.

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Dialogue Flow

Let us create a dictionary called transitions and name its initial state as start:

  • #1: transitions is a .

Add transitions to conduct a single-turn dialogue:

  • #3: the system begins the dialogue by saying, "Hello. How are you?".

  • #4: the system matches the user input with 'good'.

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All keys and values must be in the type, where literals need to be surrounded by reversed primes (e.g., '`Hello. How are you?`').

There are two ways to create a string in Python, using single quotes (e.g., 'Hello') and double quotes (e.g., "Hello"). When you use single quotes, any single quote inside the string needs to be escaped by a backslash (e.g., 'I\'m "good"!'). Similarly, when you use double quotes, any double quote needs to be escaped (e.g., "I'm \"good\"!").

Create the dialogue flow df that expects the initial state start and the final state end, which must match the names of the initial and final states in transitions:

  • #1: the import statement should be on top of the source code (see ).

  • #2:

Load the transitions to the dialogue flow df:

Finally, run the dialogue flow:

  • #1:

  1. Enter inputs such as "good", "Good", or "Good!" (separately) and see how the system responds. Does the system respond differently?

  2. How does the system respond to inputs like "fantastic" or "bad"?

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Branching

Let us add a transition such that it can also handle the input 'bad':

  • #7-9: a new transition for the 'bad' condition.

When you load the new transitions and run the dialogue flow, it now gives proper responses to both 'good' and 'bad':

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Error Handling

Even with branching, it still throws errors for other inputs. Let us add an error transition to set the default statement for all the other inputs:

  • #10-12: an error transition to generate the default response.

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Make sure to put a default error statement for every branching; otherwise, it will throw an exception during runtime, which can be detrimental.

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Code Snippet

  • #3: although Python is a dynamically-typed language, it allows you to indicate the type of a variable or a function using (since Python 3.5).

transitions = {'state': 'start'}
#5: the system responds to the user with "Glad to hear that ..." and recognizes that it is the final state end.

User inputs get automatically lowercased and tokenizedarrow-up-right before matching. Thus, the system gives the same response to those inputs.

  • If the input does not match 'good' exactly, the system throws an error because no exception is currently handled in our code.

  • S: Hello. How are you?
    U: Good!
    S: Glad to hear that you are doing well :)
    dictionaryarrow-up-right
    stringarrow-up-right
    dialogue_graph.pyarrow-up-right
    keyword vs. positional argumentsarrow-up-right
    top-level code environmentarrow-up-right
    typingarrow-up-right
    transitions = {
        'state': 'start',
        '`Hello. How are you?`': {
            'good': {
                '`Glad to hear that you are doing well :)`': 'end'
            }
        }
    }
    from emora_stdm import DialogueFlow
    df = DialogueFlow('start', end_state='end')
    df.load_transitions(transitions)
    if __name__ == '__main__':
        df.run()
    transitions = {
        'state': 'start',
        '`Hello. How are you?`': {
            'good': {
                '`Glad to hear that you are doing well :)`': 'end'
            },
            'bad': {
                '`I hope your day gets better soon :(`': 'end'
            }
        }
    }
    S: Hello. How are you?
    U: Good
    S: Glad to hear that you are doing well :)
    S: Hello. How are you?
    U: Bad
    S: I hope your day gets better soon :(
    transitions = {
        'state': 'start',
        '`Hello. How are you?`': {
            'good': {
                '`Glad to hear that you are doing well :)`': 'end'
            },
            'bad': {
                '`I hope your day gets better soon :(`': 'end'
            },
            'error': {
                '`Sorry, I didn\'t understand you.`': 'end'
            }
        }
    }
    S: Hello. How are you?
    U: It could be better.
    S: Sorry, I didn't understand you.
    from emora_stdm import DialogueFlow
    
    def state_transition() -> DialogueFlow:
        transitions = {
            'state': 'start',
            '`Hello. How are you?`': {
                'good': {
                    '`Glad to hear that you are doing well :)`': 'end'
                },
                'bad': {
                    '`I hope your day gets better soon :(`': 'end'
                },
                'error': {
                    '`Sorry, I didn\'t understand you.`': 'end'
                }
            }
        }
    
        df = DialogueFlow('start', end_state='end')
        df.load_transitions(transitions)
        return df
    
    if __name__ == '__main__':
        state_transition().run()