Sentiment Analysis In Excel With Azure Machine Learning And Power Query

You may have seen Joseph Sirosh’s blog post last week about the ability to publish Azure Machine Learning models to the Azure Marketplace, and that MS have published a number of APIs there already. There’s a new Excel add-in that can be used with these APIs but I noticed that at least one of them, the Sentiment Analysis API, can be used direct from Power Query too.

To do this, the first thing you need to do is to go to the Azure Marketplace, sign in with your Microsoft account, and subscribe to the Lexicon Based Sentiment Analysis API. The docs say you get 25000 transactions free per month although there doesn’t appear to be a way to pay for more; that said the number of transactions remaining shown on my account kept resetting, so maybe there is no limit. The API itself is straightforward: pass it a sentence to evaluate and it will return a score between –1 and 1, where 1 represents a positive sentiment and –1 is a negative sentiment. For example, the sentence “I had a good day” returns the value 1:

…whereas the sentence “I had a bad day” returns –1:

You can now go to Power Query and click From Azure Marketplace (you will need to enter your credentials at this point if this is the first time you’ve used the Azure Marketplace from Power Query):

…and then, when the Navigator pane appears, double-click on Score:

The API is exposed as a function in Power Query (I guess because it’s an OData service operation, but I’m not sure) and double-clicking on Score invokes the function. You can enter a sentence here and the Query Editor will open to show the score:

However, to do anything useful you don’t want to invoke the function just yet – you want a query that returns the function. To do this you need to edit the query. Go to the Advanced Editor and you’ll see the M code for the query will be something like this:

let
    Source = Marketplace.Subscriptions(),
    #"https://api.datamarket.azure.com/data.ashx/aml_labs/
      lexicon_based_sentiment_analysis/v1/" = 
      Source{
       [ServiceUrl="https://api.datamarket.azure.com/data.ashx/aml_labs/
       lexicon_based_sentiment_analysis/v1/"]
       }[Feeds],
    Score1 = 
       #"https://api.datamarket.azure.com/data.ashx/aml_labs/
       lexicon_based_sentiment_analysis/v1/"
       {[Name="Score"]}[Data],
    #"Invoked FunctionScore1" = Score1("I had a good day")
in
    #"Invoked FunctionScore1"

You need to remove the last line (called #”Invoked FunctionScore1”) which invokes the function, leaving:

let
    Source = Marketplace.Subscriptions(),
    #"https://api.datamarket.azure.com/data.ashx/aml_labs/
      lexicon_based_sentiment_analysis/v1/" = 
      Source{[ServiceUrl="https://api.datamarket.azure.com/data.ashx/aml_labs/
      lexicon_based_sentiment_analysis/v1/"]}[Feeds],
    Score1 = #"https://api.datamarket.azure.com/data.ashx/aml_labs/
      lexicon_based_sentiment_analysis/v1/"
      {[Name="Score"]}[Data]
in
    Score1

You can now click the Close and Load button to close the Query Editor window; you now have a function called Score that you can call in other queries. For example, take the following Excel table (called Sentences):

Click on the From Table button to load this table into Power Query, then in the Query Editor click the Add Custom Column button and add a new custom column called Sentiment Score with the expression

Score([Sentence])

You’ll then be prompted to set a data privacy level for the data you’re using, because calling this function involves sending data from your worksheet up to the API where someone could potentially see it.

Click the Continue button and set the privacy level for the workbook to Public, so that this data can be sent to the API:

Click Save and you’ll see the sentiment score has been added as a column containing a Record value. Click on the Expand icon in the SentimentScore column then OK:

And at last you’ll see the scores themselves:

Here’s the code:

let
    Source = Excel.CurrentWorkbook(){[Name="Sentences"]}[Content],
    #"Added Custom" = Table.AddColumn(Source, "SentimentScore", each Score([Sentence])),
    #"Expand SentimentScore" = 
       Table.ExpandRecordColumn(#"Added Custom", "SentimentScore", 
       {"result"}, {"SentimentScore.result"})
in
    #"Expand SentimentScore"

You can download the sample workbook here.

Of course, I couldn’t resist repeating this exercise with all of my Facebook status updates – which, of course, can be accessed from Power Query very easily. Here’s my monthly average sentiment score from June 2009 to now:

As you can see, I was in a particularly good mood this August – probably because I was on holiday for almost the whole month.