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Sentiment Analysis - Python

This guide will show you how to easily identify the sentiment and emotion of a call. This is good for POST analysis or with some simple modification, it can be used in real-time to route the caller actively.

In this guide, we will accept calls and send audio to the NLP service allowing for a web application to monitor sentiment in real-time. Sentiment is a score from 0 to 1 that identifies the caller's emotion. You point a SignalWire phone number to the /voice_entry endpoint, and it will assign a score and read it back to you. Once a call has three consecutive negative results, the API dispatches an SMS to a supervisor for assistance.

Keep in mind this is an example. However, depending on the sentiment score, you can route the call however your business sees fit, send follow-up surveys for customer satisfaction purposes, begin call recordings, and so much more. The possibilities are truly endless.

What do I need to run this application?

View the full code on our Github here!

You will need the Flask framework and the SignalWire Python SDK downloaded.

You will also need your API key from Microsoft Cognitive Services in order to use their sentiment analysis.

Running the Application

Build and Run on Docker

  1. Use our pre-built image from Docker Hub
docker pull signalwire/snippets-sentiment-analysis:python

(or build your own image)

  1. Build your image
docker build -t snippets-sentiment-analysis .
  1. Run your image
docker run --publish 5000:5000 --env-file .env snippets-sentiment-analysis
  1. The application will run on port 5000

Build and Run Natively

To run the application, execute export then run flask run.

You may need to use an SSH tunnel for testing this code if running on your local machine. – we recommend ngrok. You can learn more about how to use ngrok here.

Step by Step Code Walkthrough

In the Github repo, there are 4 files:

  • Dockerfile
  • .env file

We can ignore the dockerfile and - we will start with the .env file and then go over the file below.

Setup Your Environment File

  1. Copy from 'example.env' and fill in your values
  2. Save new file called '.env'

Your file should look something like this.

# This is your key for Microsoft cognitive services


The first part of our code is defining the function that will actually utilize Microsoft cognitive services API to analyze the sentiment of the user-given message. Calling this function with the input_text (recorded speech from the caller) and the input_language (the language of the speaker) as parameters will perform the sentiment analysis and store the response in a JSON to make it easier to query later.

def get_sentiment(input_text, input_language):
base_url = ''
path = '/v2.0/sentiment'
constructed_url = base_url + path

headers = {
'Ocp-Apim-Subscription-Key': subscription_key,
'Content-type': 'application/json',
'X-ClientTraceId': str(uuid.uuid4())

# You can pass more than one object in body.
body = {
'documents': [
'language': input_language,
'id': '1',
'text': input_text
response =, headers=headers, json=body)
return response.json()

The route /voice_entry will be used to handle incoming calls to your phone number. Here we will use Gather to gather a speech response and Say to play a prompt advising the user to begin speaking. After they are doing speaking, we will hang up the call and redirect to the /sentiment route specified in the action URL.

@app.route('/voice_entry', methods=['GET','POST'])
def voice_entry():

# instantiate a voice response
response = VoiceResponse()

# Prompt user
gather = Gather(action='/sentiment', input='speech', speechTimeout="auto", timeout="10", method='GET')

# Append say to gather to produce TTS
gather.say("Please say a phrase or statement, and we will than analyze the verbiage and tell you the sentiment. ")

# Append the gather

# Hangup the call

# return response
return str(response)

In the /sentiment route, we will get the SpeechResult parameter from the HTTP request to this route. We will use this along with the input_lang (English) as parameters for our get_sentiment() function. We will round the score to the nearest two digits and convert it into words that represent the emotion of the caller as this is more human-friendly than plain numbers. Lastly, we will use <Say> to read the result of the sentiment analysis!

@app.route('/sentiment', methods=['GET','POST'])
def sentiment():
# get speech result from user and store in input_text variable
input_text = request.values.get("SpeechResult")
input_lang = "en"
output_text = ""
output_lang = "en"

# call get sentiment function with our caller's speech as the input text and english as the language
sentimentResponse = get_sentiment(input_text, input_lang)

# Round the score to two digits
score = round(sentimentResponse['documents'][0]['score'], 2)

response = VoiceResponse()
sentimentText = ""

# Convert score into easier to understand words
if score > .9:
sentimentText = "Extremely Happy"
elif score > .8:
sentimentText = "Very Happy"
elif score > .7:
sentimentText = "Happy"
elif score > .6:
sentimentText = "Slightly Happy"
elif score > .5:
sentimentText = "Middle of Road"
elif score > .4:
sentimentText = "Slightly Unhappy"
elif score > .3:
sentimentText = "Unhappy"
elif score > .2:
sentimentText = "Very Unhappy"
sentimentText = "Extremely Unhappy"

# Return result to user
response.say("The sentiment score was " + str(score) + " which indicates user was " + sentimentText)

# return response
return str(response)

Wrap Up

Sentiment analysis is a powerful natural language processing tool that can help you get the real sentiment of your callers and make decisions based on what you find out. It can easily be used as a post-processing tool or in real-time to determine the best way to respond to the customer.

Required Resources:

Sign Up Here

If you would like to test this example out, you can create a SignalWire account and space here.

Please feel free to reach out to us on our Community Slack or create a Support ticket if you need guidance!

As Seen on LIVEWire

If you want to see a live code breakdown, explanation, and demonstration of this guide at work, click here or check it out below to watch it on YouTube! While you're there, feel free to take a look at our YouTube Channel to see other LIVEWire code and application breakdowns!