Name

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CHOOSE_LEVELS

Purpose

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This function chooses convenient values for contour levels.

Category

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Graphics

Calling Sequence

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Result = CHOOSE_LEVELS( Data )

Inputs

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Data: The array of data values, of type integer or floating
point.

Keyword Parameters

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NLEVELS: The maximum number of levels to be chosen. The default is
10.
RANGE: A two-element vector containing the FIXED
[minimum,maximum] level values. The result returned
will be a list of convenient levels within this range,
which may not entirely extend to these limits. The
default is to alter the limiting values such that they
are convenient, and thus included in the levels.

Uses

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DECIMAL_PLACE.pro
FIRST_DIGIT.pro
INTERVAL_CALC.pro
SIGN.pro
VAR_TYPE.pro

Procedure

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This function adjusts the limiting values of a level scale
and chooses the best number of levels such that the level values
are convenient decimal numbers.

Example

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Create a random data set.
y = randomn( 1, 100 )
Choose convenient levels for partitioning the data.
result = choose_levels( y )

Modification History

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  Written by: Daithi A. Stone, 2000-09-25
Modified: DAS, 2001-01-12 (switched limit value-choosing
algorithm)
Modified: DAS, 2001-05-08 (fixed limit-choosing bug)
Modified: DAS, 2002-02-06 (switched limit value-choosing
algorithm again)
Modified: DAS, 2002-02-13 (added ability to ignore NaNs)
Modified: DAS, 2002-03-12 (added NLEVELS keyword, added checks to
value-choosing)
Modified: DAS, 2002-05-07 (fixed float-integer bug)
Modified: DAS, 2002-05-19 (fixed round-off bug)
Modified: DAS, 2002-06-02 (fine-tuning level-choosing)