AFINN-based sentiment analysis for Node.js
- Performance (see benchmarks below)
- The ability to append and overwrite word / value pairs from the AFINN wordlist
- A build process that makes updating sentiment to future wordlists trivial
npm install sentiment
var sentiment = ;var r1 = ;consoledirr1; // Score: -2, Comparative: -0.666var r2 = ;consoledirr2; // Score: 4, Comparative: 1
Adding / overwriting words
You can append and/or overwrite values from AFINN by simply injecting key/value pairs into a sentiment method call:
var sentiment = ;var result =;consoledirresult; // Score: 7, Comparative: 1.75
How it works
AFINN is a list of words rated for valence with an integer between minus five (negative) and plus five (positive). Sentiment analysis is performed by cross-checking the string tokens(words, emojis) with the AFINN list and getting their respective scores. The comparative score is simply:
sum of each token / number of tokens. So for example let's take the following:
I love cats, but I am allergic to them.
That string results in the following:
score: 1comparative: 01111111111111111tokens:'i''love''cats''but''i''am''allergic''to''them'words:'allergic''love'positive:'love'negative:'allergic'
- Returned Objects
- Score: Score calculated by adding the sentiment values of recongnized words.
- Comparative: Comparative score of the input string.
- Token: All the tokens like words or emojis found in the input string.
- Words: List of words from input string that were found in AFINN list.
- Positive: List of postive words in input string that were found in AFINN list.
- Negative: List of negative words in input string that were found in AFINN list.
In this case, love has a value of 3, allergic has a value of -2, and the remaining tokens are neutral with a value of 0. Because the string has 9 tokens the resulting comparative score looks like:
(3 + -2) / 9 = 0.111111111
This approach leaves you with a mid-point of 0 and the upper and lower bounds are constrained to positive and negative 5 respectively (the same as each token! ðŸ˜¸). For example, let's imagine an incredibly "positive" string with 200 tokens and where each token has an AFINN score of 5. Our resulting comparative score would look like this:
(max positive score * number of tokens) / number of tokens (5 * 200) / 200 = 5
Tokenization works by splitting the lines of input string, then removing the special characters, and finally splitting it using spaces. This is used to get list of words in the string.
A primary motivation for designing
sentiment was performance. As such, it includes a benchmark script within the test directory that compares it against the Sentimental module which provides a nearly equivalent interface and approach. Based on these benchmarks, running on a MacBook Pro with Node v6.9.1,
sentiment is twice as fast as alternative implementations:
sentiment x 448,788 ops/sec Â±1.02%Sentimental x 240,103 ops/sec Â±5.13%
To run the benchmarks yourself:
While the accuracy provided by AFINN is quite good considering it's computational performance (see above) there is always room for improvement. Therefore the
sentiment module is open to accepting PRs which modify or amend the AFINN / Emoji datasets or implementation given that they improve accuracy and maintain similar performance characteristics. In order to establish this, we test the
sentiment module against three labelled datasets provided by UCI.
To run the validation tests yourself:
Rand Accuracy (AFINN Only)
Amazon: 0.70 IMDB: 0.76 Yelp: 0.67
Rand Accuracy (AFINN + Additions)
Amazon: 0.72 (+2%) IMDB: 0.76 (+0%) Yelp: 0.69 (+2%)