Class: Census::ResultSet

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/rboc/data.rb

Overview

A result data set

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(json = '[]') ⇒ ResultSet

Constructs a new data object from Census data returned by the API. The format of JSON should be:

[["column1", "column2", ...], [row11, row12, ...], [row21, row22, ...], ...]



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# File 'lib/rboc/data.rb', line 163

def initialize(json='[]')
  json = JSON.parse json if json.is_a? String
  @colnames, *@rows = *json
  @colmap = Hash[@colnames.zip (0..@colnames.length)]

  @geocolnames, @datacolnames = self.class.split_colnames colnames
end

Instance Attribute Details

#colnames ⇒ Object (readonly)

Returns the value of attribute colnames.



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# File 'lib/rboc/data.rb', line 157

def colnames
  @colnames
end

#rows ⇒ Object (readonly)

Returns the value of attribute rows.



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# File 'lib/rboc/data.rb', line 157

def rows
  @rows
end

Class Method Details

.split_colnames(colnames) ⇒ Object

Split a list of column names into geographic columns and data columns



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# File 'lib/rboc/data.rb', line 141

def self.split_colnames(colnames)
  geocolnames = []
  datacolnames = []
  colnames.each do |s|
    if Geography::LEVELS.include? s
      geocolnames << s
    else
      datacolnames << s
    end
  end

  [geocolnames, datacolnames]
end

Instance Method Details

#==(other) ⇒ Object 



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# File 'lib/rboc/data.rb', line 207

def ==(other)
  other.is_a?(ResultSet) && self.colnames == other.colnames && self.rows == other.rows
end

#each ⇒ Object 



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# File 'lib/rboc/data.rb', line 171

def each
  @rows.each do |row|
    yield Hash[@colnames.zip row]
  end
end

#merge!(json) ⇒ Object

Merges an existing Census data set with additional data returned from the API. Currently, this method assumes columns and rows are returned in a consistent order given the same geography.



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# File 'lib/rboc/data.rb', line 181

def merge!(json)
  json = JSON.parse json if json.is_a? String
  colnames, *rows = *json
  colmap = Hash[colnames.zip (0..colnames.length)]
  geocolnames, datacolnames = self.class.split_colnames colnames

  if geocolnames != @geocolnames
    raise ArgumentError, "Mismatched geographies"
  end

  @rows.map!.with_index do |row, i|
    if  @geocolnames.any? {|s| row[@colmap[s]] != rows[i][colmap[s]]}
      raise ArgumentError, "Mismatched rows"
    end

    row += datacolnames.map {|s| rows[i][colmap[s]]}
  end

  n = @colnames.length
  @colmap.merge! Hash[datacolnames.zip (n..(n+datacolnames.length))]
  @colnames += datacolnames
  @datacolnames += datacolnames

  self
end