Export data frame to different common formats

Stores and load data in various of data format. See 'Details' for limitations.

Usage

export_table(
  x,
  file,
  format = c("auto", "csv", "csv.zip", "h5", "fst", "json", "rds", "yaml"),
  ...
)

import_table(
  file,
  format = c("auto", "csv", "csv.zip", "h5", "fst", "json", "rds", "yaml"),
  ...
)

Arguments

x: data table to be saved to file
file: file to store the data
format: data storage format, default is 'auto' (infer from the file extension); other choices are 'csv', 'csv.zip', 'h5', 'fst', 'json', 'rds', 'yaml'
...: parameters passed to other functions

Value

The normalized path for export_table, and a data.table for import_table

Details

The format 'rds', 'h5', 'fst', 'json', and 'yaml' try to preserve the first-level column attributes. Factors will be preserved in these formats. Such property does not exist in 'csv', 'csv.zip' formats.

Open-data formats are 'h5', 'csv', 'csv.zip', 'json', 'yaml'. These formats require the table elements to be native types (numeric, character, factor, etc.).

'rds', 'h5', and 'fst' can store large data sets. 'fst' is the best choice is performance and file size are the major concerns. 'rds' preserves all the properties of the table.

Examples


x <- data.table::data.table(
  a = rnorm(10),
  b = letters[1:10],
  c = 1:10,
  d = factor(LETTERS[1:10])
)

f <- tempfile(fileext = ".csv.zip")

export_table(x = x, file = f)

y <- import_table(file = f)

str(x)
#> Classes ‘data.table’ and 'data.frame':	10 obs. of  4 variables:
#>  $ a: num  -0.0886 0.8048 -0.9736 -0.3458 -1.5931 ...
#>  $ b: chr  "a" "b" "c" "d" ...
#>  $ c: int  1 2 3 4 5 6 7 8 9 10
#>  $ d: Factor w/ 10 levels "A","B","C","D",..: 1 2 3 4 5 6 7 8 9 10
#>  - attr(*, ".internal.selfref")=<externalptr> 
str(y)
#> Classes ‘data.table’ and 'data.frame':	10 obs. of  4 variables:
#>  $ a: num  -0.0886 0.8048 -0.9736 -0.3458 -1.5931 ...
#>  $ b: chr  "a" "b" "c" "d" ...
#>  $ c: int  1 2 3 4 5 6 7 8 9 10
#>  $ d: chr  "A" "B" "C" "D" ...
#>  - attr(*, ".internal.selfref")=<externalptr> 

# clean up
unlink(f)