In a post on Sitepoint Allan MacGregor gives a good practical example on how to work with PHP-ML, a machine learning library for PHP.

As of late, it seems everyone and their proverbial grandma is talking about Machine Learning. Your social media feeds are inundated with posts about ML, Python, TensorFlow, Spark, Scala, Go and so on; and if you are anything like me, you might be wondering, what about PHP? Yes, what about Machine Learning and PHP? Fortunately, someone was crazy enough not only to ask that question, but to also develop a generic machine learning library that we can use in our next project. In this post we are going take a look at PHP-ML – a machine learning library for PHP – and we’ll write a sentiment analysis class that we can later reuse for our own chat or tweet bot.

https://www.sitepoint.com/how-to-analyze-tweet-sentiments-with-php-machine-learning/