Class FasterCSV::Table
In: lib/faster_csv.rb
Parent: Object

A FasterCSV::Table is a two-dimensional data structure for representing CSV documents. Tables allow you to work with the data by row or column, manipulate the data, and even convert the results back to CSV, if needed.

All tables returned by FasterCSV will be constructed from this class, if header row processing is activated.

Methods

<<   ==   []   []=   by_col   by_col!   by_col_or_row   by_col_or_row!   by_row   by_row!   delete   delete_if   each   headers   inspect   new   push   to_a   to_csv   to_s   values_at  

Included Modules

Enumerable

Attributes

mode  [R]  The current access mode for indexing and iteration.
table  [R]  Internal data format used to compare equality.

Public Class methods

Construct a new FasterCSV::Table from array_of_rows, which are expected to be FasterCSV::Row objects. All rows are assumed to have the same headers.

A FasterCSV::Table object supports the following Array methods through delegation:

  • empty?()
  • length()
  • size()

[Source]

# File lib/faster_csv.rb, line 426
      def initialize(array_of_rows)
        @table = array_of_rows
        @mode  = :col_or_row
      end

Public Instance methods

Adds a new row to the bottom end of this table. You can provide an Array, which will be converted to a FasterCSV::Row (inheriting the table‘s headers()), or a FasterCSV::Row.

This method returns the table for chaining.

[Source]

# File lib/faster_csv.rb, line 624
      def <<(row_or_array)
        if row_or_array.is_a? Array  # append Array
          @table << Row.new(headers, row_or_array)
        else                         # append Row
          @table << row_or_array
        end

        self  # for chaining
      end

Returns true if all rows of this table ==() other‘s rows.

[Source]

# File lib/faster_csv.rb, line 703
      def ==(other)
        @table == other.table
      end

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!().

Columns are returned as an Array of values. Altering that Array has no effect on the table.

[Source]

# File lib/faster_csv.rb, line 540
      def [](index_or_header)
        if @mode == :row or  # by index
           (@mode == :col_or_row and index_or_header.is_a? Integer)
          @table[index_or_header]
        else                 # by header
          @table.map { |row| row[index_or_header] }
        end
      end

In the default mixed mode, this method assigns rows for index access and columns for header access. You can force the index association by first calling by_col!() or by_row!().

Rows may be set to an Array of values (which will inherit the table‘s headers()) or a FasterCSV::Row.

Columns may be set to a single value, which is copied to each row of the column, or an Array of values. Arrays of values are assigned to rows top to bottom in row major order. Excess values are ignored and if the Array does not have a value for each row the extra rows will receive a nil.

Assigning to an existing column or row clobbers the data. Assigning to new columns creates them at the right end of the table.

[Source]

# File lib/faster_csv.rb, line 565
      def []=(index_or_header, value)
        if @mode == :row or  # by index
           (@mode == :col_or_row and index_or_header.is_a? Integer)
          if value.is_a? Array
            @table[index_or_header] = Row.new(headers, value)
          else
            @table[index_or_header] = value
          end
        else                 # set column
          if value.is_a? Array  # multiple values
            @table.each_with_index do |row, i|
              if row.header_row?
                row[index_or_header] = index_or_header
              else
                row[index_or_header] = value[i]
              end
            end
          else                  # repeated value
            @table.each do |row|
              if row.header_row?
                row[index_or_header] = index_or_header
              else
                row[index_or_header] = value
              end
            end
          end
        end
      end

Returns a duplicate table object, in column mode. This is handy for chaining in a single call without changing the table mode, but be aware that this method can consume a fair amount of memory for bigger data sets.

This method returns the duplicate table for chaining. Don‘t chain destructive methods (like []=()) this way though, since you are working with a duplicate.

[Source]

# File lib/faster_csv.rb, line 452
      def by_col
        self.class.new(@table.dup).by_col!
      end

Switches the mode of this table to column mode. All calls to indexing and iteration methods will work with columns until the mode is changed again.

This method returns the table and is safe to chain.

[Source]

# File lib/faster_csv.rb, line 462
      def by_col!
        @mode = :col

        self
      end

Returns a duplicate table object, in mixed mode. This is handy for chaining in a single call without changing the table mode, but be aware that this method can consume a fair amount of memory for bigger data sets.

This method returns the duplicate table for chaining. Don‘t chain destructive methods (like []=()) this way though, since you are working with a duplicate.

[Source]

# File lib/faster_csv.rb, line 477
      def by_col_or_row
        self.class.new(@table.dup).by_col_or_row!
      end

Switches the mode of this table to mixed mode. All calls to indexing and iteration methods will use the default intelligent indexing system until the mode is changed again. In mixed mode an index is assumed to be a row reference while anything else is assumed to be column access by headers.

This method returns the table and is safe to chain.

[Source]

# File lib/faster_csv.rb, line 489
      def by_col_or_row!
        @mode = :col_or_row

        self
      end

Returns a duplicate table object, in row mode. This is handy for chaining in a single call without changing the table mode, but be aware that this method can consume a fair amount of memory for bigger data sets.

This method returns the duplicate table for chaining. Don‘t chain destructive methods (like []=()) this way though, since you are working with a duplicate.

[Source]

# File lib/faster_csv.rb, line 504
      def by_row
        self.class.new(@table.dup).by_row!
      end

Switches the mode of this table to row mode. All calls to indexing and iteration methods will work with rows until the mode is changed again.

This method returns the table and is safe to chain.

[Source]

# File lib/faster_csv.rb, line 514
      def by_row!
        @mode = :row

        self
      end

Removes and returns the indicated column or row. In the default mixed mode indices refer to rows and everything else is assumed to be a column header. Use by_col!() or by_row!() to force the lookup.

[Source]

# File lib/faster_csv.rb, line 652
      def delete(index_or_header)
        if @mode == :row or  # by index
           (@mode == :col_or_row and index_or_header.is_a? Integer)
          @table.delete_at(index_or_header)
        else                 # by header
          @table.map { |row| row.delete(index_or_header).last }
        end
      end

Removes any column or row for which the block returns true. In the default mixed mode or row mode, iteration is the standard row major walking of rows. In column mode, interation will yield two element tuples containing the column name and an Array of values for that column.

This method returns the table for chaining.

[Source]

# File lib/faster_csv.rb, line 669
      def delete_if(&block)
        if @mode == :row or @mode == :col_or_row  # by index
          @table.delete_if(&block)
        else                                      # by header
          to_delete = Array.new
          headers.each_with_index do |header, i|
            to_delete << header if block[[header, self[header]]]
          end
          to_delete.map { |header| delete(header) }
        end

        self  # for chaining
      end

In the default mixed mode or row mode, iteration is the standard row major walking of rows. In column mode, interation will yield two element tuples containing the column name and an Array of values for that column.

This method returns the table for chaining.

[Source]

# File lib/faster_csv.rb, line 692
      def each(&block)
        if @mode == :col
          headers.each { |header| block[[header, self[header]]] }
        else
          @table.each(&block)
        end

        self  # for chaining
      end

Returns the headers for the first row of this table (assumed to match all other rows). An empty Array is returned for empty tables.

[Source]

# File lib/faster_csv.rb, line 524
      def headers
        if @table.empty?
          Array.new
        else
          @table.first.headers
        end
      end

[Source]

# File lib/faster_csv.rb, line 740
      def inspect
        "#<#{self.class} mode:#{@mode} row_count:#{to_a.size}>"
      end

A shortcut for appending multiple rows. Equivalent to:

  rows.each { |row| self << row }

This method returns the table for chaining.

[Source]

# File lib/faster_csv.rb, line 641
      def push(*rows)
        rows.each { |row| self << row }

        self  # for chaining
      end

Returns the table as an Array of Arrays. Headers will be the first row, then all of the field rows will follow.

[Source]

# File lib/faster_csv.rb, line 711
      def to_a
        @table.inject([headers]) do |array, row|
          if row.header_row?
            array
          else
            array + [row.fields]
          end
        end
      end

Returns the table as a complete CSV String. Headers will be listed first, then all of the field rows.

This method assumes you want the Table.headers(), unless you explicitly pass :write_headers => false.

[Source]

# File lib/faster_csv.rb, line 728
      def to_csv(options = Hash.new)
        wh = options.fetch(:write_headers, true)
        @table.inject(wh ? [headers.to_csv(options)] : [ ]) do |rows, row|
          if row.header_row?
            rows
          else
            rows + [row.fields.to_csv(options)]
          end
        end.join
      end
to_s(options = Hash.new)

Alias for to_csv

The mixed mode default is to treat a list of indices as row access, returning the rows indicated. Anything else is considered columnar access. For columnar access, the return set has an Array for each row with the values indicated by the headers in each Array. You can force column or row mode using by_col!() or by_row!().

You cannot mix column and row access.

[Source]

# File lib/faster_csv.rb, line 603
      def values_at(*indices_or_headers)
        if @mode == :row or  # by indices
           ( @mode == :col_or_row and indices_or_headers.all? do |index|
                                        index.is_a?(Integer)         or
                                        ( index.is_a?(Range)         and
                                          index.first.is_a?(Integer) and
                                          index.last.is_a?(Integer) )
                                      end )
          @table.values_at(*indices_or_headers)
        else                 # by headers
          @table.map { |row| row.values_at(*indices_or_headers) }
        end
      end

[Validate]