Increase or decrease the number of chunks in the disk.frame

Increase or decrease the number of chunks in the disk.frame

rechunk(
  df,
  nchunks = disk.frame::nchunks(df),
  outdir = attr(df, "path", exact = TRUE),
  shardby = NULL,
  overwrite = TRUE
)

Arguments

df

the disk.frame to rechunk

nchunks

number of chunks

outdir

the output directory

shardby

the shardkeys

overwrite

overwrite the output directory

Examples

# create a disk.frame with 2 chunks in tempdir()
cars.df = as.disk.frame(cars, nchunks = 2)

# re-chunking cars.df to 3 chunks, done "in-place" to the same folder as cars.df
rechunk(cars.df, 3)
#> files have been backed up to temporary dir C:\Users\RTX2080\AppData\Local\Temp\RtmpCo1OFr\back_up_tmp_dir2b64104a78f2. You can recover there files until you restart your R session
#> path: "C:\Users\RTX2080\AppData\Local\Temp\RtmpCo1OFr\file2b64fd96c35.df"
#> nchunks: 3
#> nrow (at source): 50
#> ncol (at source): 2

new_path = tempfile(fileext = ".df")
# re-chunking cars.df to 4 chunks, shard by speed, and done "out-of-place" to a new directory
cars2.df = rechunk(cars.df, 4, outdir=new_path, shardby = "speed")
#> Appending disk.frames: 

# clean up cars.df
delete(cars.df)
delete(cars2.df)