Hello,
Thanks for reaching out to us! The Text Analytics API is a cloud-based service that provides Natural Language Processing (NLP) features for text mining and text analysis, including: sentiment analysis, opinion mining, key phrase extraction, language detection, and named entity recognition.
https://learn.microsoft.com/en-us/azure/cognitive-services/text-analytics/overview
There is not that function like a key word filter. I would recommend you use application like Excel to filter the original data set.
If you want to do some Machine Learning related work, there is a filter function in Azure Machin Learning studio as well : https://learn.microsoft.com/en-us/azure/machine-learning/studio-module-reference/apply-filter
Regards,
Yutong