Writing

CSV.write — Function
CSV.write(file, table; kwargs...) => file
table |> CSV.write(file; kwargs...) => file

Write a Tables.jl interface input to a csv file, given as an IO argument or String/FilePaths.jl type representing the file name to write to. Alternatively, CSV.RowWriter creates a row iterator, producing a csv-formatted string for each row in an input table.

Supported keyword arguments include:

  • bufsize::Int=2^22: The length of the buffer to use when writing each csv-formatted row; default 4MB; if a row is larger than the bufsize an error is thrown
  • delim::Union{Char, String}=',': a character or string to print out as the file's delimiter
  • quotechar::Char='"': ascii character to use for quoting text fields that may contain delimiters or newlines
  • openquotechar::Char: instead of quotechar, use openquotechar and closequotechar to support different starting and ending quote characters
  • escapechar::Char='"': ascii character used to escape quote characters in a text field
  • missingstring::String="": string to print for missing values
  • dateformat=Dates.default_format(T): the date format string to use for printing out Date & DateTime columns
  • append=false: whether to append writing to an existing file/IO, if true, it will not write column names by default
  • compress=false: compress the written output using standard gzip compression (provided by the CodecZlib.jl package); note that a compression stream can always be provided as the first "file" argument to support other forms of compression; passing compress=true is just for convenience to avoid needing to manually setup a GzipCompressorStream
  • writeheader=!append: whether to write an initial row of delimited column names, not written by default if appending
  • header: pass a list of column names (Symbols or Strings) to use instead of the column names of the input table
  • newline='\n': character or string to use to separate rows (lines in the csv file)
  • quotestrings=false: whether to force all strings to be quoted or not
  • decimal='.': character to use as the decimal point when writing floating point numbers
  • transform=(col,val)->val: a function that is applied to every cell e.g. we can transform all nothing values to missing using (col, val) -> something(val, missing)
  • bom=false: whether to write a UTF-8 BOM header (0xEF 0xBB 0xBF) or not
  • partition::Bool=false: by passing true, the table argument is expected to implement Tables.partitions and the file argument can either be an indexable collection of IO, file Strings, or a single file String that will have an index appended to the name

Examples

using CSV, Tables, DataFrames

# write out a DataFrame to csv file
df = DataFrame(rand(10, 10), :auto)
CSV.write("data.csv", df)

# write a matrix to an in-memory IOBuffer
io = IOBuffer()
mat = rand(10, 10)
CSV.write(io, Tables.table(mat))
source
CSV.RowWriter — Type
CSV.RowWriter(table; kwargs...)

Creates an iterator that produces csv-formatted strings for each row in the input table.

Supported keyword arguments include:

  • bufsize::Int=2^22: The length of the buffer to use when writing each csv-formatted row; default 4MB; if a row is larger than the bufsize an error is thrown
  • delim::Union{Char, String}=',': a character or string to print out as the file's delimiter
  • quotechar::Char='"': ascii character to use for quoting text fields that may contain delimiters or newlines
  • openquotechar::Char: instead of quotechar, use openquotechar and closequotechar to support different starting and ending quote characters
  • escapechar::Char='"': ascii character used to escape quote characters in a text field
  • missingstring::String="": string to print for missing values
  • dateformat=Dates.default_format(T): the date format string to use for printing out Date & DateTime columns
  • header: pass a list of column names (Symbols or Strings) to use instead of the column names of the input table
  • newline='\n': character or string to use to separate rows (lines in the csv file)
  • quotestrings=false: whether to force all strings to be quoted or not
  • decimal='.': character to use as the decimal point when writing floating point numbers
  • transform=(col,val)->val: a function that is applied to every cell e.g. we can transform all nothing values to missing using (col, val) -> something(val, missing)
  • bom=false: whether to write a UTF-8 BOM header (0xEF 0xBB 0xBF) or not
source