Obtain one chunk by chunk id
get_chunk(...)
# S3 method for disk.frame
get_chunk(df, n, keep = NULL, full.names = FALSE, ..., partitioned_info = NULL)passed to fst::read_fst or whichever read function is used in the backend
a disk.frame
the chunk id. If numeric then matches by number, if character then returns the chunk with the same name as n
the columns to keep
whether n is the full path to the chunks or just a relative path file name. Ignored if n is numeric
for internal use only. It's a data.frame used to help with filtering by partitions
cars.df = as.disk.frame(cars, nchunks = 2)
get_chunk(cars.df, 1)
#> speed dist
#> 1: 4 2
#> 2: 4 10
#> 3: 7 4
#> 4: 7 22
#> 5: 8 16
#> 6: 9 10
#> 7: 10 18
#> 8: 10 26
#> 9: 10 34
#> 10: 11 17
#> 11: 11 28
#> 12: 12 14
#> 13: 12 20
#> 14: 12 24
#> 15: 12 28
#> 16: 13 26
#> 17: 13 34
#> 18: 13 34
#> 19: 13 46
#> 20: 14 26
#> 21: 14 36
#> 22: 14 60
#> 23: 14 80
#> 24: 15 20
#> 25: 15 26
#> speed dist
get_chunk(cars.df, 2)
#> speed dist
#> 1: 15 54
#> 2: 16 32
#> 3: 16 40
#> 4: 17 32
#> 5: 17 40
#> 6: 17 50
#> 7: 18 42
#> 8: 18 56
#> 9: 18 76
#> 10: 18 84
#> 11: 19 36
#> 12: 19 46
#> 13: 19 68
#> 14: 20 32
#> 15: 20 48
#> 16: 20 52
#> 17: 20 56
#> 18: 20 64
#> 19: 22 66
#> 20: 23 54
#> 21: 24 70
#> 22: 24 92
#> 23: 24 93
#> 24: 24 120
#> 25: 25 85
#> speed dist
get_chunk(cars.df, 1, keep = "speed")
#> speed
#> 1: 4
#> 2: 4
#> 3: 7
#> 4: 7
#> 5: 8
#> 6: 9
#> 7: 10
#> 8: 10
#> 9: 10
#> 10: 11
#> 11: 11
#> 12: 12
#> 13: 12
#> 14: 12
#> 15: 12
#> 16: 13
#> 17: 13
#> 18: 13
#> 19: 13
#> 20: 14
#> 21: 14
#> 22: 14
#> 23: 14
#> 24: 15
#> 25: 15
#> speed
# if full.names = TRUE then the full path to the chunk need to be provided
get_chunk(cars.df, file.path(attr(cars.df, "path"), "1.fst"), full.names = TRUE)
#> speed dist
#> 1: 4 2
#> 2: 4 10
#> 3: 7 4
#> 4: 7 22
#> 5: 8 16
#> 6: 9 10
#> 7: 10 18
#> 8: 10 26
#> 9: 10 34
#> 10: 11 17
#> 11: 11 28
#> 12: 12 14
#> 13: 12 20
#> 14: 12 24
#> 15: 12 28
#> 16: 13 26
#> 17: 13 34
#> 18: 13 34
#> 19: 13 46
#> 20: 14 26
#> 21: 14 36
#> 22: 14 60
#> 23: 14 80
#> 24: 15 20
#> 25: 15 26
#> speed dist
# clean up cars.df
delete(cars.df)