RocCurve

Plots a ROC curve, or a curve with sensitivity on the Y-axis and 1 - specificity on the X-axis. This is a useful metric for determining how well a test statistic discriminates between two classes. The following assumptions are made in this implementation:

1. For some cutoff value c and test statistic T, your decision rule is of the form "Class A if T larger than c, Class B if T smaller than c".

2. In the case of ties, i.e. if class A and class B both have an identical value, linear interpolation is used. This is because changing the value of c infinitesimally will change both sensitivity and specificity in these cases.

class RocCurve : LineGraph {

static RocCurve opCall(R1 classATs, R2 classBTs);

double auroc();

Figure toLabeledFigure();

}

Members

Functions

auroc double auroc(): Returns the area under the ROC curve.
toLabeledFigure Figure toLabeledFigure(): Default title is the area under the curve. Default x label is "1 - Specificity". Default y label is "Sensitivity".

Static functions

opCall RocCurve opCall(R1 classATs, R2 classBTs): Create a RocCurve. classATs are the test statistics that are "supposed" to be bigger, classBTs are the test statistics that are "supposed to be smaller. Both R1 and R2 must be input ranges with elements implicitly convertible to double.

Inherited Members

From LineGraph

lineColor Color lineColor(): The color of the line. The default is black.
lineColor This lineColor(Color newColor): Setter
lineWidth uint lineWidth(): The width of the line. The default is 1.
lineWidth This lineWidth(uint newWidth): Setter
errorWidth double errorWidth(): Error bar width, relative to the total width of the plot. Must be between 0 and 1. If it's out of bounds, it will be set to the default of 0.05. If no error bars are to be drawn, this option is ignored.
errorWidth This errorWidth(double newWidth): Setter
pointSymbol char pointSymbol(): The symbol that should be used to denote a data point. Setting this to ' ' (a space) turns off point symbols and plots the line only. By default the point symbol is a space, so no point symbol is plotted..
pointSymbol This pointSymbol(char newSymbol): Setter
pointColor Color pointColor(): The color of each point on the plot.
pointColor This pointColor(Color newColor): Setter.
pointSize int pointSize(): The size of a point. (Default 20).
pointSize This pointSize(int newSize): Setter
opCall LineGraph opCall(R1 x, R2 y): Factory method for creating a LineGraph. x and y must both be input ranges of the same length, with elements implicitly convertible to doubles. Note that they are copied inside the factory, so changes to the original ranges after calling this factory will not affect the plot.
opCall LineGraph opCall(R y): Convenience factory method that produces a LineGraph with a default X axis numbered 1, 2, ..., N, where N is the number of data points, and no error bars. This is mostly useful for quick and dirty plots.
opCall LineGraph opCall(R1 x, R2 y, R3 lowerErrors, R4 upperErrors): Create a LineGraph with error bars. lowerErrors and upperErrors must be input ranges with elements implicitly convertible to double for error bars to be shown. Any other value, such as null or 0, will result in no error bars being shown. Therefore, to only show, for example, upper erros, simply pass in null or 0 for the lower errors.
scaleX void scaleX(double scaleFactor): Scale this object by a factor of scaleFactor in the X direction. This is useful for getting it onto the same scale as another plot.
scaleY void scaleY(double scaleFactor): Scale this object by a factor of scaleFactor in the Y direction. * This is useful for getting it onto the same scale as another plot.
shiftX void shiftX(double shiftBy): Shift this graph by shiftBy units in the X direction. This is useful for getting it onto the same scale as another plot.
shiftY void shiftY(double shiftBy): Shift this graph by shiftBy units in the Y direction. This is useful for getting it onto the same scale as another plot.