Coyote Graphics Routines

Date: Fri Apr 10 11:24:17 2015

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cgtaylordiagram.pro

includes main-level program

top cgTaylorDiagram

Graphics

cgTaylorDiagram [, /ADDCMD] [, C_CORRELATION=string] [, C_STDDEV=string] [, C_REF=string] [, C_SYMBOL=string] [, LABELS=string] [, /NOERASE] [, OUTPUT=string] [, /OVERPLOT] [, POSITION=float] [, REF_STDDEV=float] [, /RMS_CIRCLES_OFF] [, RMS_FORMAT=string] [, RMS_INCREMENT=float] [, /RMS_LABELS_OFF] [, STDDEV_MAX=float] [, SYMBOL=integer] [, SYMSIZE=float] [, /WINDOW]

The program implements a Taylor Diagram in IDL direct graphics. Addtional information can be found in this article. From the 2001 IPCC Reoprt:

"Taylor diagrams provide a way of graphically summarizing how closely a pattern (or a set of patterns) matches observations. The similarity between two patterns is quantified in terms of their correlation, their centered root-mean-square difference and the amplitude of their variations (represented by their standard deviations). These diagrams are especially useful in evaluating multiple aspects of complex models or in gauging the relative skill of many different models." "In general, the Taylor diagram characterizes the statistical relationship between two fields, a "test" field (often representing a field simulated by a model) and a "reference" field (usually representing “truth”, based on observations)." "The two-dimensional space of the Taylor diagram can represent three different statistics simultaneously:
- The centered RMS difference, - The correlation, - The standard deviation
The reference to Karl Taylor's original paper explaining the diagram is Taylor, K.E., Summarizing multiple aspects of model performance in a single diagram, J. Geophys. Res., 106, 7183-7192, 2001.

Here is a simple, but complete, explanation of the diagram.

Parameters

stddev in required type=float

An array of standard deviations for the points that will be plotted on the diagram. This array must be the same length as the correlation array and the Labels array, if it is used.

correlation in required type=float

An array of correlation coefficients for the points that will be plotted on the diagram. This array must be the same length as the stddev array and the Labels array, if it is used.

Keywords

Set this keyword to add the command to the resizeable graphics window cgWindow.

C_CORRELATION in optional type=string default=grn7

The name of the color used for the correlation lines on the diagram.

C_STDDEV in optional type=string default=blu7

The name of the color used for the standard deviation lines on the diagram.

C_REF in optional type=string default=pur7

The name of the color used for the observed reference line on the diagram.

C_SYMBOL in optional type=string default=red

The name of the color used for the point symbols on the diagram.

LABELS in optional type=string

An array of string labels for the points that will be plotted on the diagram. This array must be the same length as the stddev array and the correlation array.

NOERASE in optional type=boolean default=0

Set this keyword if you don't want the Taylor Diagram plot to erase what is already on the display.

OUTPUT in optional type=string

The name of an output file to write the Taylor Diagram to. The type of file is taken from the file extension. For example, OUTPUT='mydiagram.png'. It is assumed that Ghostscript and ImageMagick have been installed properly for all raster file output. If the Output keyword is used, nothing is drawn on the display. This keyword cannot be used with the Overplot keyword.

OVERPLOT in optional type=boolean default=0

Set this keyword to overplot onto an already existing Taylor Diagram. Many keywords are ignored if this keyword is set. Only the data is drawn. The Output keyword cannot be used if overplotting.

POSITION in optional type=float

A four-element, normalized array giving the position of the plot in the display window: [x0,y0,x1,y1].

REF_STDDEV in optional type=float default=1.0

The reference standard deviation. This is typically the "observed" or "model" value. A scalar.

RMS_CIRCLES_OFF in optional type=boolean default=0

Set this keyword to prevent the drawing of the RMS circles that radiate out from the observed RMS value.

RMS_FORMAT in optional type=string default=(I0)

Set this keyword to a format string that is used for format the RMS circle labels.

RMS_INCREMENT in optional type=float default=1.0

The RMS circles are drawn from the observed RMS value, using this value as an increment of the circle radius.

RMS_LABELS_OFF in optional type=boolean default=0

Set this keyword to prevent the drawing of the RMS circle labels. If this keyword is set, only the RMS circles are drawn.

STDDEV_MAX in optional type=float

The maximum standard deviation to plot on the graph.

SYMBOL in optional type=integer default=16

The symbol used for the data points on the diagram. Any symbol supported by cgSymCat.

SYMSIZE in optional type=float default=1.5

The size of the symbol used for the data points on the diagram.

WINDOW in optional type=boolean default=0

Set this keyword to replace all the commands in a current cgWindow or to create a new cgWindow for displaying this command.

Examples

Here is how to use this program:

labels = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H'] ; Point labels. stddev = [1.4, 0.9, 1.0, 1.272, 1.1, 0.95, 1.08, 0.5] ; Standard Deviations correlation = [0.8, 0.9, 0.65, 0.74, 0.91, 0.98, 0.85, 0.35] ; Correlations ref_std = 1.0 ; Reference standard (observed) stddev_max = 1.5 ; Standard Deviation maximum cgTaylorDiagram, stddev, correlation, REF_STDDEV=ref_std, STDDEV_MAX=stddev_max, LABELS=labels

Author information

Author:

FANNING SOFTWARE CONSULTING:

David W. Fanning 1645 Sheely Drive Fort Collins, CO 80526 USA Phone: 970-221-0438 E-mail: david@idlcoyote.com Coyote's Guide to IDL Programming: http://www.idlcoyote.com