Guesses whether a raw RSF CSV file is UTF-8 or a Latin-1 variant. Used by clean_period_1(), clean_period_2(), and clean_period_3() because RSF has switched export encoding across years without notice (e.g. 2002-2021 exports are UTF-8 despite once being assumed ISO-8859-1, and 2025-2026 arrived as ISO-8859-1 while 2022-2024 were UTF-8).
Details
Uses readr::guess_encoding(), which ranks candidate encodings by confidence. Explicitly detects UTF-8/US-ASCII and the ISO-8859-1 family (ISO-8859-1, windows-1252, latin1) and normalizes all to one of these two outcomes. Raises an error if: - readr::guess_encoding() returns zero candidates (truly indeterminate), or - the top candidate is neither UTF-8/ASCII nor the ISO-8859-1 family (an unexpected encoding, typically indicating data corruption or a source format change).
This explicit design prevents silent misidentification: if RSF ever introduces a third encoding, or a file is corrupted, the error is visible at parse time rather than allowing bad data downstream.