Class: CTioga2::Data::DataPoint

Inherits:
Object
  • Object
show all
Defined in:
lib/ctioga2/data/point.rb

Overview

This class represents a datapoint, ie. an index in a given DataSet.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(dataset, index) ⇒ DataPoint

Creates a DataPoint with the given information.



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# File 'lib/ctioga2/data/point.rb', line 33

def initialize(dataset,index)
  @dataset = dataset
  @index = index
end

Instance Attribute Details

#dataset ⇒ Object

The Dataset object the point is in



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# File 'lib/ctioga2/data/point.rb', line 27

def dataset
  @dataset
end

#index ⇒ Object

The index of the data point within the Dataset



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# File 'lib/ctioga2/data/point.rb', line 30

def index
  @index
end

Class Method Details

.from_text(plotmaker, text, dataset = nil) ⇒ Object

Creates a DataPoint object based on the following text specification. It needs a reference to a plotmaker, since it accesses the data stack.

Specification: (<em>dataset</em>)?(relative|@index)



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# File 'lib/ctioga2/data/point.rb', line 43

def self.from_text(plotmaker, text, dataset = nil)
  if text =~ /^(?:\s*\{([^}]+)\})?\s*(?:([.\d]+)|@(\d+))\s*$/
    which = $1 || -1
    if $2
      rel = Float($2)
    else
      idx = $3.to_i
    end
    dataset ||= plotmaker.data_stack.stored_dataset(which)
    
    if ! dataset
      raise "Invalid or empty dataset: #{which}"
    end
    if rel
      idx = (rel * (dataset.x.values.size - 1)).to_i
    end
    return DataPoint.new(dataset, idx)
  else
    raise "Not a valid datapoint specification: '#{text}'"
  end
end

Instance Method Details

#dx(navg = 3) ⇒ Object

Returns the average value of the difference between two consecutive X values



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# File 'lib/ctioga2/data/point.rb', line 140

def dx(navg = 3)
  xvect = @dataset.x.values
  di = (navg-1)/2
  navg = 2*di + 1

  idx = usable_index(di, xvect.size)
  return (xvect[idx+di]-xvect[idx-di])/navg
end

#point ⇒ Object 



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# File 'lib/ctioga2/data/point.rb', line 73

def point
  return [self.x, self.y]
end

#slope(navg = 3) ⇒ Object

Returns the value of the slope around the datapoint. This is obtained using a linear regression, so it should be rather reliable.



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# File 'lib/ctioga2/data/point.rb', line 112

def slope(navg = 3)
  xvect = @dataset.x.values
  yvect = @dataset.y.values
  di = (navg-1)/2
  navg = 2*di + 1

  idx = usable_index(di, xvect.size)

  sx = 0
  sxx = 0
  sxy = 0
  sy = 0

  (idx-di).upto(idx+di) do |i|
    sx += xvect[i]
    sy += yvect[i]
    sxx += xvect[i]**2
    sxy += xvect[i] * yvect[i]
  end
  if sxx*navg == sx*sx
    return 1
  else
    return (sxy * navg - sx*sy)/(sxx * navg - sx*sx)
  end
end

#x ⇒ Object 



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# File 'lib/ctioga2/data/point.rb', line 65

def x
  return @dataset.x.values[@index]
end

#x_val(navg = 3) ⇒ Object

Returns the averaged X value around the datapoint



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# File 'lib/ctioga2/data/point.rb', line 78

def x_val(navg = 3)

  xvect = @dataset.x.values
  di = (navg-1)/2
  navg = 2*di + 1

  idx = usable_index(di, xvect.size)

  xval = 0
  (idx-di).upto(idx+di) do |i|
    xval += xvect[i]
  end
  return xval/(navg)
end

#y ⇒ Object 



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# File 'lib/ctioga2/data/point.rb', line 69

def y
  return @dataset.y.values[@index]
end

#y_val(navg = 3) ⇒ Object

Returns the averaged Y value around the datapoint



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# File 'lib/ctioga2/data/point.rb', line 95

def y_val(navg = 3)
  yvect = @dataset.y.values
  di = (navg-1)/2
  navg = 2*di + 1

  idx = usable_index(di, yvect.size)

  yval = 0
  (idx-di).upto(idx+di) do |i|
    yval += yvect[i]
  end
  return yval/(navg)
end