Usage

Installation

fstflowchat requires pygraphviz. To install this on a colab notebook use the following commands

!apt install libgraphviz-dev # installs graphviz plus development libraries
!pip install fstflowchat
import fstflowchat as ffc

Creating a dialog graph

Here is an example dialog graph specified in graphviz.

digraph library_help {
start -> how_can_I_help                [label="null:welcome_msg_with_question"]
how_can_I_help -> vpn         [label="is_digital_request:ask_about_vpn"]
vpn   -> library_databases [label="is_affirmative:give_resource_link_and_reprompt"]
vpn -> vpn_help [label="not_affirmative:give_vpn_help"]
#vpn -> vpn [label="not_has_vpn:give_vpn_help"]
vpn_help -> it_issue [label="not_ready:file_it_issue"]
vpn_help -> library_databases [label="is_ready:give_resource_link"]
ask_again -> library_databases [label="is_digital_request:give_resource_link_and_reprompt"]
library_databases -> bye    [label="not_affirmative_nor_question:help_complete"]
library_databases -> ask_again [label="is_affirmative:repeat_question"]
library_databases -> library_databases [label="is_question:give_resource_link_and_reprompt"]
it_issue-> bye [label="not_affirmative_nor_question:help_complete"]
}

This will produce a dialog graph that looks like this:

The labels of the edges do most of the work of the dialog. The first part of the edge label before the “:” is the transition test function. This is the name of a python function that takes a string input and returns a True or False. The first transition, null() returns true for any input:

def null(input_: str) -> bool:
  """this null transition will be true for any arguments, or no input

  It's not quite the same as a null transition in an FST, but it's a
  similar idea

  """
  return True

This null transition sets up the dialog for the dialog system’s first prompt. The dialog system’s output is defined by the second component of the edge label after the “:”, the transition output function. This the name of a python function that takes a string input and returns a string output. The string input of the fuction represents the user’s input and the output represents the system’s output. However for the first transition, the input is empty. The states represent when the system is waiting for user input. For the transition from the first state, we give the dialog system an empty string as an input. Sometimes, we don’t need the users input, especially for the output function, but the functions for transition tests and outputs always have a string input. Here is a transition output function that returns the system’s initial prompt: “Welcome to the library, how may I help you?”

def welcome_msg_with_question(input_: str) -> str:
  return "Welcome to the library, how may I help you?"

For a full example see the noebook example