Export data to CSV file(s)
Usage
write_csv_polars(
.data,
file,
...,
include_bom = FALSE,
include_header = TRUE,
separator = ",",
line_terminator = "\n",
quote_char = "\"",
batch_size = 1024,
datetime_format = NULL,
date_format = NULL,
time_format = NULL,
float_precision = NULL,
null_value = "",
quote_style = "necessary"
)Arguments
- .data
A Polars DataFrame.
- file
File path to which the result should be written.
- ...
Ignored.
- include_bom
Whether to include UTF-8 BOM (byte order mark) in the CSV output.
- include_header
Whether to include header in the CSV output.
- separator
Separate CSV fields with this symbol.
- line_terminator
String used to end each row.
- quote_char
Byte to use as quoting character.
- batch_size
Number of rows that will be processed per thread.
- datetime_format
A format string, with the specifiers defined by the chrono Rust crate. If no format specified, the default fractional-second precision is inferred from the maximum timeunit found in the frame’s Datetime cols (if any).
- date_format
A format string, with the specifiers defined by the chrono Rust crate.
- time_format
A format string, with the specifiers defined by the chrono Rust crate.
- float_precision
Number of decimal places to write, applied to both Float32 and Float64 datatypes.
- null_value
A string representing null values (defaulting to the empty string).
- quote_style
Determines the quoting strategy used.
"necessary"(default): This puts quotes around fields only when necessary. They are necessary when fields contain a quote, delimiter or record terminator. Quotes are also necessary when writing an empty record (which is indistinguishable from a record with one empty field). This is the default."always": This puts quotes around every field."non_numeric": This puts quotes around all fields that are non-numeric. Namely, when writing a field that does not parse as a valid float or integer, then quotes will be used even if they aren`t strictly necessary."never": This never puts quotes around fields, even if that results in invalid CSV data (e.g. by not quoting strings containing the separator).
Details
Partitioned output
It is possible to export data to multiple files based on various parameters,
such as the values of some variables, or such that each file has a maximum
number of rows. See partition_by() for more details.
Examples
dest <- tempfile(fileext = ".csv")
mtcars |>
as_polars_df() |>
write_csv_polars(dest)
read.csv(dest)
#> mpg cyl disp hp drat wt qsec vs am gear carb
#> 1 21.0 6 160.0 110 3.90 2.620 16.46 0 1 4 4
#> 2 21.0 6 160.0 110 3.90 2.875 17.02 0 1 4 4
#> 3 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1
#> 4 21.4 6 258.0 110 3.08 3.215 19.44 1 0 3 1
#> 5 18.7 8 360.0 175 3.15 3.440 17.02 0 0 3 2
#> 6 18.1 6 225.0 105 2.76 3.460 20.22 1 0 3 1
#> 7 14.3 8 360.0 245 3.21 3.570 15.84 0 0 3 4
#> 8 24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 2
#> 9 22.8 4 140.8 95 3.92 3.150 22.90 1 0 4 2
#> 10 19.2 6 167.6 123 3.92 3.440 18.30 1 0 4 4
#> 11 17.8 6 167.6 123 3.92 3.440 18.90 1 0 4 4
#> 12 16.4 8 275.8 180 3.07 4.070 17.40 0 0 3 3
#> 13 17.3 8 275.8 180 3.07 3.730 17.60 0 0 3 3
#> 14 15.2 8 275.8 180 3.07 3.780 18.00 0 0 3 3
#> 15 10.4 8 472.0 205 2.93 5.250 17.98 0 0 3 4
#> 16 10.4 8 460.0 215 3.00 5.424 17.82 0 0 3 4
#> 17 14.7 8 440.0 230 3.23 5.345 17.42 0 0 3 4
#> 18 32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 1
#> 19 30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 2
#> 20 33.9 4 71.1 65 4.22 1.835 19.90 1 1 4 1
#> 21 21.5 4 120.1 97 3.70 2.465 20.01 1 0 3 1
#> 22 15.5 8 318.0 150 2.76 3.520 16.87 0 0 3 2
#> 23 15.2 8 304.0 150 3.15 3.435 17.30 0 0 3 2
#> 24 13.3 8 350.0 245 3.73 3.840 15.41 0 0 3 4
#> 25 19.2 8 400.0 175 3.08 3.845 17.05 0 0 3 2
#> 26 27.3 4 79.0 66 4.08 1.935 18.90 1 1 4 1
#> 27 26.0 4 120.3 91 4.43 2.140 16.70 0 1 5 2
#> 28 30.4 4 95.1 113 3.77 1.513 16.90 1 1 5 2
#> 29 15.8 8 351.0 264 4.22 3.170 14.50 0 1 5 4
#> 30 19.7 6 145.0 175 3.62 2.770 15.50 0 1 5 6
#> 31 15.0 8 301.0 335 3.54 3.570 14.60 0 1 5 8
#> 32 21.4 4 121.0 109 4.11 2.780 18.60 1 1 4 2