diff --git a/lib/csv/table.rb b/lib/csv/table.rb index e6c1ee11fa..a6059ce60a 100644 --- a/lib/csv/table.rb +++ b/lib/csv/table.rb @@ -144,14 +144,91 @@ class CSV end end + # :call-seq: + # table[n] -> row + # table[range] -> array_of_rows + # table[header] -> array_of_fields # - # In the default mixed mode, this method returns rows for index access and - # columns for header access. You can force the index association by first - # calling by_col!() or by_row!(). + # Returns data from the table; does not modify the table. # - # Columns are returned as an Array of values. Altering that Array has no - # effect on the table. + # --- # + # The expression table[n], where +n+ is a non-negative \Integer, + # returns the +n+th row of the table, if that row exists, + # and if the access mode is :row or :col_or_row: + # source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n" + # table = CSV.parse(source, headers: true) + # table.by_row! # => # + # table[1] # => # + # table.by_col_or_row! # => # + # table[1] # => # + # + # Counts backward from the last row if +n+ is negative: + # table[-1] # => # + # + # Returns +nil+ if +n+ is too large or too small: + # table[4] # => nil + # table[-4] => nil + # + # Raises an exception if the access mode is :row + # and +n+ is not an + # {Integer-convertible object}[https://docs.ruby-lang.org/en/master/implicit_conversion_rdoc.html#label-Integer-Convertible+Objects]. + # table.by_row! # => # + # # Raises TypeError (no implicit conversion of String into Integer): + # table['Name'] + # + # --- + # + # The expression table[range], where +range+ is a Range object, + # returns rows from the table, beginning at row range.first, + # if those rows exist, and if the access mode is :row or :col_or_row: + # source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n" + # table = CSV.parse(source, headers: true) + # table.by_row! # => # + # rows = table[1..2] # => # + # rows # => [#, #] + # table.by_col_or_row! # => # + # rows = table[1..2] # => # + # rows # => [#, #] + # + # If there are too few rows, returns all from range.first to the end: + # rows = table[1..50] # => # + # rows # => [#, #] + # + # Special case: if range.start == table.size, returns an empty \Array: + # table[table.size..50] # => [] + # + # If range.end is negative, calculates the ending index from the end: + # rows = table[0..-1] + # rows # => [#, #, #] + # + # If range.start is negative, calculates the starting index from the end: + # rows = table[-1..2] + # rows # => [#] + # + # If range.start is larger than table.size, returns +nil+: + # table[4..4] # => nil + # + # --- + # + # The expression table[header], where +header+ is a \String, + # returns column values (\Array of \Strings) if the column exists + # and if the access mode is :col or :col_or_row: + # source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n" + # table = CSV.parse(source, headers: true) + # table.by_col! # => # + # table['Name'] # => ["foo", "bar", "baz"] + # table.by_col_or_row! # => # + # col = table['Name'] + # col # => ["foo", "bar", "baz"] + # + # Modifying the returned column values does not modify the table: + # col[0] = 'bat' + # col # => ["bat", "bar", "baz"] + # table['Name'] # => ["foo", "bar", "baz"] + # + # Returns an \Array of +nil+ values if there is no such column: + # table['Nosuch'] # => [nil, nil, nil] def [](index_or_header) if @mode == :row or # by index (@mode == :col_or_row and (index_or_header.is_a?(Integer) or index_or_header.is_a?(Range)))