data-science etc.

parquet -> data.table

files = dir(pattern = ".parquet")
dat = rbindlist(lapply(files, arrow::read_parquet))
# dat = rbindlist(lapply(files, arrow::read_parquet, col_select=1:10))

write_parquet(dat, sink = "file.parquet")

// https://stata2r.github.io/data_table/#read-and-write-parquet

also: see setDT