Name

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KDM_RANGE

Purpose

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  This function converts a variable or array from one scale to
  another. The input data is assumed to be on the scale
  [min(data),max(data)] although this can be customized. It is
  converted to a new scale of the range
  [rangemin,rangemax]. Overflow and underflow can be customized.

Category

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Data massaging

Calling Sequence

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result = KDM_RANGE( data, from, to )

Inputs

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DATA This is your input data set, either a single number or
multi-dimensional array
  FROM: A 2 element array specifying the [min,max] input range of DATA
  TO: A 2 element array specifying the desired output range of DATA

Keyword Parameters

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  UNDERFLOW: This is value to set data points that convert to less
              than RANGEMIN
  OVERFLOW: This is value to set data points that convert to more
            than RANGEMAX

Outputs

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  This function returns the input array (data) scaled from FROM to TO

Restrictions

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  Output is always float.

Procedure

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  Scale the input data to [0,1], then multiply by the desired
  [minrange,maxrange]

Example

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  data = [-1, 0, 0.1, 1]
  ; scale data to [0,100]
  print, kdm_range( data, from=minmax(data), to=[0,100] )
  ; -1 goes to 0, 1 goes to 100, and everything else betwixt...
  ; scale data to [-1,0] output, but force the data input range to
  ; [0,1]. Underflow (the -1 input value) should be set to -999
  print, kdm_range( data,from=[-1,1],to=[-1, 0], datamin=0, underflow=-999 )

Modification History

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  Written by: Ken Mankoff, 2007-05.
2007-07-17: KDM. Re-wrote to use from and to arrays