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A general description is here.
‘deparse(..)’, ‘dump(..)’, and ‘dput(x, control="all")’ now include using control option ‘"digits17"’ which typically ensures 1:1 invertibility. New option ‘control = "exact"’ ensures numeric exact invertibility via ‘"hexDigits"’.
R now uses a ‘stringsAsFactors = FALSE’ default, and hence by default no longer converts strings to factors in calls to ‘data.frame()’ and ‘read.table()’.
When loading data sets via ‘read.table()’, ‘data()’ now uses ‘LC_COLLATE=C’ to ensure locale independent results for possible string to factor conversions.