I use AbbyR package in R to extract text from pdf sources for my research project. My research focused on the impact of European strategic culture on autonomous European Union defense cooperation. These pdf sources will be added to other text files collected for the project for computer assisted text analysis in R, including topic modelling and sentiment analysis.
For more information on some of the tools being used, see below:
ABBYY API is used for OCR, where text sources are not available. ocrsdk.com
Sood, Gaurav. AbbyyR: Access to Abbyy Optical Character Recognition (OCR) API (version 0.5.5), 2019. https://CRAN.R-project.org/package=abbyyR.