How to choose literature for language learning?

Literature selection tool analysis literature in the context of its difficulty on Interlinear books. It helps you choose literature to read even if you're still learning foreign languages.

The literature difficulty works for Portuguese, Swedish, Russian, French and a bunch of other languages. It checks for these factors:

• grammatical difficulty of literature - the length of words, sentences, sentence structure, paragraph structure (I think) - all computed in terms of acknowledged scores which exist;
• vocabulary difficulty - frequency vocabulary assessment in terms of different scores and factors, together with tables and data.

Here is a sample of the kind of analysis Interlinear books provides about a book: