Decode a stream of comma-separated lines into a table.

Options

These are the options:

• :separator – The separator token to use, defaults to ?,. Must be a codepoint (syntax: ? + (your separator)).
• :strip_fields – When set to true, will strip whitespace from cells. Defaults to false.
• :preprocessor – Which preprocessor to use: :lines (default) -> Will preprocess line by line input respecting escape sequences :codepoints -> Will preprocess codepoint by codepoint input respecting escape sequences :none -> Will not preprocess input and expects line by line input with multiple line escape sequences aggregated to one line
• :escape_max_lines – How many lines to maximally aggregate for multiline escapes. Defaults to a 1000.
• :num_workers – The number of parallel operations to run when producing the stream.
• :worker_work_ratio – The available work per worker, defaults to 5. Higher rates will mean more work sharing, but might also lead to work fragmentation slowing down the queues.
• :headers – When set to true, will take the first row of the csv and use it as header values. When set to a list, will use the given list as header values. When set to false (default), will use no header values. When set to anything but false, the resulting rows in the matrix will be maps instead of lists.

Examples

Convert a filestream into a stream of rows, inlining errors into the stream:

iex> "../test/fixtures/docs/valid.csv"
iex> |> Path.expand(__DIR__)
iex> |> File.stream!
iex> |> CSV.decode
iex> |> Enum.take(2)
[{:ok, ["a","b","c"]}, {:ok, ["d","e","f"]}]

Convert a filestream into a stream of rows, throwing an error on invalid rows:

iex> "../test/fixtures/docs/valid.csv"
iex> |> Path.expand(__DIR__)
iex> |> File.stream!
iex> |> CSV.decode!
iex> |> Enum.take(2)
[["a","b","c"], ["d","e","f"]]

Convert a filestream into a stream of rows in order of the given stream:

iex> "../test/fixtures/docs/valid.csv"
iex> |> Path.expand(__DIR__)
iex> |> File.stream!
iex> |> CSV.decode!(num_workers: 1)
iex> |> Enum.take(2)
[["a","b","c"], ["d","e","f"]]

Map an existing stream of lines separated by a token to a stream of rows with a header row:

iex> ["a;b","c;d", "e;f"]
iex> |> Stream.map(&(&1))
iex> |> CSV.decode!(separator: ?;, headers: true)
iex> |> Enum.take(2)
[%{"a" => "c", "b" => "d"}, %{"a" => "e", "b" => "f"}]

Map an existing stream of lines separated by a token to a stream of rows with a given header row:

iex> ["a;b","c;d", "e;f"]
iex> |> Stream.map(&(&1))
iex> |> CSV.decode!(separator: ?;, headers: [:x, :y])
iex> |> Enum.take(2)
[%{:x => "a", :y => "b"}, %{:x => "c", :y => "d"}]

Encode a table stream into a stream of RFC 4180 compliant CSV lines for writing to a file or other IO.

Options

These are the options:

• :separator – The separator token to use, defaults to ?,. Must be a codepoint (syntax: ? + (your separator)).
• :delimiter – The delimiter token to use, defaults to \r\n. Must be a string.

Examples

Convert a stream of rows with cells into a stream of lines:

iex> [~w(a b), ~w(c d)]
iex> |> CSV.encode
iex> |> Enum.take(2)
["a,b\r\n", "c,d\r\n"]

Convert a stream of rows with cells with escape sequences into a stream of lines:

iex> [["a\nb", "\tc"], ["de", "\tf\""]]
iex> |> CSV.encode(separator: ?\t, delimiter: "\n")
iex> |> Enum.take(2)
["\"a\\nb\"\t\"\\tc\"\n", "de\t\"\\tf\"\"\"\n"]