CSV
RFC 4180 compliant CSV parsing and encoding for Elixir. Allows to specify other separators, so it could also be named: TSV, but it isn’t.
Summary↑
decode(stream, options \\ []) | Decode a stream of comma-separated lines into a table.
If the number of parallel operations (set via the option |
encode(stream, options \\ []) | Encode a table stream into a stream of RFC 4180 compliant CSV lines for writing to a file or other IO |
Functions
Decode a stream of comma-separated lines into a table.
If the number of parallel operations (set via the option :num_pipes
and defaulting to 8)
is greater than 1, this will produce the rows of the file out of order. If parallel operations
are set to one, lexing and parsing are still parallelised, which results in better performance.
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 ` `. Must be a string.:strip_cells
– When set to true, will strip whitespace from cells. Defaults to false.:num_pipes
– The number of parallel operations to run when producing the stream. If set to 1, the stream will produce the CSV lines in order at the cost of performance. Defaults to8
.:headers
– When set totrue
, 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 tofalse
(default), will use no header values. When set to anything butfalse
, the resulting rows in the matrix will be maps instead of lists.
Examples
Convert a filestream into a stream of rows:
iex> File.stream!("data.csv") |>
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> File.stream!("data.csv") |>
iex> CSV.decode(num_pipes: 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 ` `. 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: ? , delimiter: "\n") |>
iex> Enum.take(2)
["\"a\nb\"\t\"\tc\"\n", "de\t\"\tf\"\"\"\n"]