This issue aims to fix some errors in R examples and make them up-to-date in docs and example modules.
- Remove the wrong usage of map. We need to use `lapply` in `SparkR` if needed. However, `lapply` is private now. The correct usage will be added later.
- Fix the wrong example in Section `Generic Load/Save Functions` of `docs/sql-programming-guide.md` for consistency.
- Fix datatypes in `sparkr.md`.
- Update data results
- Replace deprecated functions: jsonFile -> read.json, parquetFile -> read.parquet
- Use up-to-date R-like functions: loadDF -> read.df, saveDF -> write.df, saveAsParquetFile -> write.parquet
- Replace `SparkR DataFrame` with `SparkDataFrame` in `dataframe.R` and `data-manipulation.R`.
- Other minor syntax fixes and typos.