To obtain a data set with bioactivity values and annotated assay information, ChEMBL (version 34) was used. Assays were described by the following properties: description, assay_type, assay_tax_id, bao_format, confidence_score, curated_by, pref_name, standard_type. Only entries from binding (B) and functional (F) assays were kept. This resulted in 1,277,311 unique assay entries with 1,142,320 unique descriptions. Inspection of the assay description lengths showed that description length is right-skewed and most descriptions have fewer than 500 characters (Figure ). Descriptions beyond this length often contain whole experimental protocols and therefore deviate from most other descriptions. Therefore, we removed assay descriptions when they contained more than 500 characters, a step which filtered out 2441 unique assay descriptions.