Class: FasterCSV::Table
- Inherits:
-
Object
- Object
- FasterCSV::Table
- Extended by:
- Forwardable
- Includes:
- Enumerable
- Defined in:
- lib/faster_csv.rb
Overview
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.
Instance Attribute Summary collapse
-
#mode ⇒ Object
readonly
The current access mode for indexing and iteration.
Instance Method Summary collapse
-
#<<(row_or_array) ⇒ Object
Adds a new row to the bottom end of this table.
-
#==(other) ⇒ Object
Returns
true
if all rows of this table ==()other
‘s rows. -
#[](index_or_header) ⇒ Object
In the default mixed mode, this method returns rows for index access and columns for header access.
-
#[]=(index_or_header, value) ⇒ Object
In the default mixed mode, this method assigns rows for index access and columns for header access.
-
#by_col ⇒ Object
Returns a duplicate table object, in column mode.
-
#by_col! ⇒ Object
Switches the mode of this table to column mode.
-
#by_col_or_row ⇒ Object
Returns a duplicate table object, in mixed mode.
-
#by_col_or_row! ⇒ Object
Switches the mode of this table to mixed mode.
-
#by_row ⇒ Object
Returns a duplicate table object, in row mode.
-
#by_row! ⇒ Object
Switches the mode of this table to row mode.
-
#delete(index_or_header) ⇒ Object
Removes and returns the indicated column or row.
-
#delete_if(&block) ⇒ Object
Removes any column or row for which the block returns
true
. -
#each(&block) ⇒ Object
In the default mixed mode or row mode, iteration is the standard row major walking of rows.
-
#headers ⇒ Object
Returns the headers for the first row of this table (assumed to match all other rows).
-
#initialize(array_of_rows) ⇒ Table
constructor
Construct a new FasterCSV::Table from
array_of_rows
, which are expected to be FasterCSV::Row objects. - #inspect ⇒ Object
-
#push(*rows) ⇒ Object
A shortcut for appending multiple rows.
-
#to_a ⇒ Object
Returns the table as an Array of Arrays.
-
#to_csv(options = Hash.new) ⇒ Object
(also: #to_s)
Returns the table as a complete CSV String.
-
#values_at(*indices_or_headers) ⇒ Object
The mixed mode default is to treat a list of indices as row access, returning the rows indicated.
Constructor Details
#initialize(array_of_rows) ⇒ Table
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()
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# File 'lib/faster_csv.rb', line 408 def initialize(array_of_rows) @table = array_of_rows @mode = :col_or_row end |
Instance Attribute Details
#mode ⇒ Object (readonly)
The current access mode for indexing and iteration.
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# File 'lib/faster_csv.rb', line 414 def mode @mode end |
Instance Method Details
#<<(row_or_array) ⇒ Object
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.
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# File 'lib/faster_csv.rb', line 606 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 |
#==(other) ⇒ Object
Returns true
if all rows of this table ==() other
‘s rows.
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# File 'lib/faster_csv.rb', line 685 def ==(other) @table == other.table end |
#[](index_or_header) ⇒ Object
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.
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# File 'lib/faster_csv.rb', line 522 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 |
#[]=(index_or_header, value) ⇒ Object
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.
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# File 'lib/faster_csv.rb', line 547 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 |
#by_col ⇒ Object
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.
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# File 'lib/faster_csv.rb', line 434 def by_col self.class.new(@table.dup).by_col! end |
#by_col! ⇒ Object
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.
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# File 'lib/faster_csv.rb', line 444 def by_col! @mode = :col self end |
#by_col_or_row ⇒ Object
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.
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# File 'lib/faster_csv.rb', line 459 def by_col_or_row self.class.new(@table.dup).by_col_or_row! end |
#by_col_or_row! ⇒ Object
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.
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# File 'lib/faster_csv.rb', line 471 def by_col_or_row! @mode = :col_or_row self end |
#by_row ⇒ Object
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.
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# File 'lib/faster_csv.rb', line 486 def by_row self.class.new(@table.dup).by_row! end |
#by_row! ⇒ Object
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.
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# File 'lib/faster_csv.rb', line 496 def by_row! @mode = :row self end |
#delete(index_or_header) ⇒ Object
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.
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# File 'lib/faster_csv.rb', line 634 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 |
#delete_if(&block) ⇒ Object
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.
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# File 'lib/faster_csv.rb', line 651 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 |
#each(&block) ⇒ Object
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.
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# File 'lib/faster_csv.rb', line 674 def each(&block) if @mode == :col headers.each { |header| block[[header, self[header]]] } else @table.each(&block) end self # for chaining end |
#headers ⇒ Object
Returns the headers for the first row of this table (assumed to match all other rows). An empty Array is returned for empty tables.
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# File 'lib/faster_csv.rb', line 506 def headers if @table.empty? Array.new else @table.first.headers end end |
#inspect ⇒ Object
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# File 'lib/faster_csv.rb', line 722 def inspect "#<#{self.class} mode:#{@mode} row_count:#{to_a.size}>" end |
#push(*rows) ⇒ Object
A shortcut for appending multiple rows. Equivalent to:
rows.each { |row| self << row }
This method returns the table for chaining.
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# File 'lib/faster_csv.rb', line 623 def push(*rows) rows.each { |row| self << row } self # for chaining end |
#to_a ⇒ Object
Returns the table as an Array of Arrays. Headers will be the first row, then all of the field rows will follow.
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# File 'lib/faster_csv.rb', line 693 def to_a @table.inject([headers]) do |array, row| if row.header_row? array else array + [row.fields] end end end |
#to_csv(options = Hash.new) ⇒ Object Also known as: to_s
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
.
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# File 'lib/faster_csv.rb', line 710 def to_csv( = Hash.new) wh = .fetch(:write_headers, true) @table.inject(wh ? [headers.to_csv()] : [ ]) do |rows, row| if row.header_row? rows else rows + [row.fields.to_csv()] end end.join end |
#values_at(*indices_or_headers) ⇒ Object
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.
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# File 'lib/faster_csv.rb', line 585 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 |