A CSV::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 CSV
will be constructed from this class, if header row processing is activated.
Constructs a new CSV::Table
from array_of_rows
, which are expected to be CSV::Row
objects. All rows are assumed to have the same headers.
The optional headers
parameter can be set to Array of headers. If headers aren't set, headers are fetched from CSV::Row
objects. Otherwise, headers() method will return headers being set in headers argument.
A CSV::Table
object supports the following Array methods through delegation:
empty?()
length()
size()
# File csv/table.rb, line 31 def initialize(array_of_rows, headers: nil) @table = array_of_rows @headers = headers unless @headers if @table.empty? @headers = [] else @headers = @table.first.headers end end @mode = :col_or_row end
If row_or_array
is a CSV::Row object, it is appended to the table:
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n" table = CSV.parse(source, headers: true) table << CSV::Row.new(table.headers, ['bat', 3]) table[3] # => #<CSV::Row "Name":"bat" "Value":3>
If row_or_array
is an Array, it is used to create a new CSV::Row object which is then appended to the table:
table << ['bam', 4] table[4] # => #<CSV::Row "Name":"bam" "Value":4>
# File csv/table.rb, line 370 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 each row of self
==
the corresponding row of other_table
, otherwise, false
.
The access mode does no affect the result.
Equal tables:
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n" table = CSV.parse(source, headers: true) other_table = CSV.parse(source, headers: true) table == other_table # => true
Different row count:
other_table.delete(2) table == other_table # => false
Different last row:
other_table << ['bat', 3] table == other_table # => false
# File csv/table.rb, line 563 def ==(other) return @table == other.table if other.is_a? CSV::Table @table == other end
Returns data from the table; does not modify 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! # => #<CSV::Table mode:row row_count:4> table[1] # => #<CSV::Row "Name":"bar" "Value":"1"> table.by_col_or_row! # => #<CSV::Table mode:col_or_row row_count:4> table[1] # => #<CSV::Row "Name":"bar" "Value":"1">
Counts backward from the last row if n
is negative:
table[-1] # => #<CSV::Row "Name":"baz" "Value":"2">
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.
table.by_row! # => #<CSV::Table mode:row row_count:4> # 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! # => #<CSV::Table mode:row row_count:4> rows = table[1..2] # => #<CSV::Row "Name":"bar" "Value":"1"> rows # => [#<CSV::Row "Name":"bar" "Value":"1">, #<CSV::Row "Name":"baz" "Value":"2">] table.by_col_or_row! # => #<CSV::Table mode:col_or_row row_count:4> rows = table[1..2] # => #<CSV::Row "Name":"bar" "Value":"1"> rows # => [#<CSV::Row "Name":"bar" "Value":"1">, #<CSV::Row "Name":"baz" "Value":"2">]
If there are too few rows, returns all from range.first
to the end:
rows = table[1..50] # => #<CSV::Row "Name":"bar" "Value":"1"> rows # => [#<CSV::Row "Name":"bar" "Value":"1">, #<CSV::Row "Name":"baz" "Value":"2">]
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 # => [#<CSV::Row "Name":"foo" "Value":"0">, #<CSV::Row "Name":"bar" "Value":"1">, #<CSV::Row "Name":"baz" "Value":"2">]
If range.start
is negative, calculates the starting index from the end:
rows = table[-1..2] rows # => [#<CSV::Row "Name":"baz" "Value":"2">]
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! # => #<CSV::Table mode:col row_count:4> table['Name'] # => ["foo", "bar", "baz"] table.by_col_or_row! # => #<CSV::Table mode:col_or_row row_count:4> 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]
# File csv/table.rb, line 232 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))) @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 CSV::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.
# File csv/table.rb, line 257 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 unless index_or_header.is_a? Integer index = @headers.index(index_or_header) || @headers.size @headers[index] = index_or_header end 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.
# File csv/table.rb, line 66 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.
# File csv/table.rb, line 76 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.
# File csv/table.rb, line 91 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.
# File csv/table.rb, line 103 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.
# File csv/table.rb, line 118 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.
# File csv/table.rb, line 128 def by_row! @mode = :row self end
If the access mode is :row
or :col_or_row
, and each argument is either an Integer or a Range, returns deleted rows. Otherwise, returns deleted columns data.
In either case, the returned values are in the order specified by the arguments. Arguments may be repeated.
Returns rows as an Array of CSV::Row objects.
One index:
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n" table = CSV.parse(source, headers: true) deleted_values = table.delete(0) deleted_values # => [#<CSV::Row "Name":"foo" "Value":"0">]
Two indexes:
table = CSV.parse(source, headers: true) deleted_values = table.delete(2, 0) deleted_values # => [#<CSV::Row "Name":"baz" "Value":"2">, #<CSV::Row "Name":"foo" "Value":"0">]
Returns columns data as column Arrays.
One header:
table = CSV.parse(source, headers: true) deleted_values = table.delete('Name') deleted_values # => ["foo", "bar", "baz"]
Two headers:
table = CSV.parse(source, headers: true) deleted_values = table.delete('Value', 'Name') deleted_values # => [["0", "1", "2"], ["foo", "bar", "baz"]]
# File csv/table.rb, line 442 def delete(*indexes_or_headers) if indexes_or_headers.empty? raise ArgumentError, "wrong number of arguments (given 0, expected 1+)" end deleted_values = indexes_or_headers.map do |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 if index_or_header.is_a? Integer @headers.delete_at(index_or_header) else @headers.delete(index_or_header) end @table.map { |row| row.delete(index_or_header).last } end end if indexes_or_headers.size == 1 deleted_values[0] else deleted_values end end
Removes rows or columns for which the block returns a truthy value; returns self
.
Removes rows when the access mode is :row
or :col_or_row
; calls the block with each CSV::Row object:
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n" table = CSV.parse(source, headers: true) table.by_row! # => #<CSV::Table mode:row row_count:4> table.size # => 3 table.delete_if {|row| row['Name'].start_with?('b') } table.size # => 1
Removes columns when the access mode is :col
; calls the block with each column as a 2-element array containing the header and an Array of column fields:
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n" table = CSV.parse(source, headers: true) table.by_col! # => #<CSV::Table mode:col row_count:4> table.headers.size # => 2 table.delete_if {|column_data| column_data[1].include?('2') } table.headers.size # => 1
Returns a new Enumerator if no block is given:
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n" table = CSV.parse(source, headers: true) table.delete_if # => #<Enumerator: #<CSV::Table mode:col_or_row row_count:4>:delete_if>
# File csv/table.rb, line 492 def delete_if(&block) return enum_for(__method__) { @mode == :row or @mode == :col_or_row ? size : headers.size } unless block_given? if @mode == :row or @mode == :col_or_row # by index @table.delete_if(&block) else # by header deleted = [] headers.each do |header| deleted << delete(header) if yield([header, self[header]]) end end self # for chaining end
Extracts the nested value specified by the sequence of index
or header
objects by calling dig at each step, returning nil if any intermediate step is nil.
# File csv/table.rb, line 602 def dig(index_or_header, *index_or_headers) value = self[index_or_header] if value.nil? nil elsif index_or_headers.empty? value else unless value.respond_to?(:dig) raise TypeError, "#{value.class} does not have \#dig method" end value.dig(*index_or_headers) end end
Calls the block with each row or column; returns self
.
When the access mode is :row
or :col_or_row
, calls the block with each CSV::Row object:
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n" table = CSV.parse(source, headers: true) table.by_row! # => #<CSV::Table mode:row row_count:4> table.each {|row| p row }
Output:
#<CSV::Row "Name":"foo" "Value":"0"> #<CSV::Row "Name":"bar" "Value":"1"> #<CSV::Row "Name":"baz" "Value":"2">
When the access mode is :col
, calls the block with each column as a 2-element array containing the header and an Array of column fields:
table.by_col! # => #<CSV::Table mode:col row_count:4> table.each {|column_data| p column_data }
Output:
["Name", ["foo", "bar", "baz"]] ["Value", ["0", "1", "2"]]
Returns a new Enumerator if no block is given:
table.each # => #<Enumerator: #<CSV::Table mode:col row_count:4>:each>
# File csv/table.rb, line 533 def each(&block) return enum_for(__method__) { @mode == :col ? headers.size : size } unless block_given? if @mode == :col headers.each { |header| yield([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). The headers Array passed to CSV::Table.new
is returned for empty tables.
# File csv/table.rb, line 139 def headers if @table.empty? @headers.dup else @table.first.headers end end
Shows the mode and size of this table in a US-ASCII String.
# File csv/table.rb, line 617 def inspect "#<#{self.class} mode:#{@mode} row_count:#{to_a.size}>".encode("US-ASCII") end
A shortcut for appending multiple rows. Equivalent to:
rows.each {|row| self << row }
Each argument may be either a CSV::Row object or an Array:
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n" table = CSV.parse(source, headers: true) rows = [ CSV::Row.new(table.headers, ['bat', 3]), ['bam', 4] ] table.push(*rows) table[3..4] # => [#<CSV::Row "Name":"bat" "Value":3>, #<CSV::Row "Name":"bam" "Value":4>]
# File csv/table.rb, line 396 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.
# File csv/table.rb, line 572 def to_a array = [headers] @table.each do |row| array.push(row.fields) unless row.header_row? end array 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
.
# File csv/table.rb, line 588 def to_csv(write_headers: true, **options) array = write_headers ? [headers.to_csv(**options)] : [] @table.each do |row| array.push(row.fields.to_csv(**options)) unless row.header_row? end array.join("") end
If the access mode is :row
or :col_or_row
, and each argument is either an Integer or a Range, returns rows. Otherwise, returns columns data.
In either case, the returned values are in the order specified by the arguments. Arguments may be repeated.
Returns rows as an Array of CSV::Row objects.
No argument:
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n" table = CSV.parse(source, headers: true) table.values_at # => []
One index:
values = table.values_at(0) values # => [#<CSV::Row "Name":"foo" "Value":"0">]
Two indexes:
values = table.values_at(2, 0) values # => [#<CSV::Row "Name":"baz" "Value":"2">, #<CSV::Row "Name":"foo" "Value":"0">]
One Range:
values = table.values_at(1..2) values # => [#<CSV::Row "Name":"bar" "Value":"1">, #<CSV::Row "Name":"baz" "Value":"2">]
Ranges and indexes:
values = table.values_at(0..1, 1..2, 0, 2) pp values
Output:
[#<CSV::Row "Name":"foo" "Value":"0">, #<CSV::Row "Name":"bar" "Value":"1">, #<CSV::Row "Name":"bar" "Value":"1">, #<CSV::Row "Name":"baz" "Value":"2">, #<CSV::Row "Name":"foo" "Value":"0">, #<CSV::Row "Name":"baz" "Value":"2">]
Returns columns data as row Arrays, each consisting of the specified columns data for that row:
values = table.values_at('Name') values # => [["foo"], ["bar"], ["baz"]] values = table.values_at('Value', 'Name') values # => [["0", "foo"], ["1", "bar"], ["2", "baz"]]
# File csv/table.rb, line 342 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