Neural Network Toolbox™

Process matrices by mapping row minimum and maximum values to [-1 1]

Syntax

• [Y,PS] = mapminmax(YMIN,YMAX)
  [Y,PS] = mapminmax(X,FP)
  Y = mapminmax('apply',X,PS)
  X = mapminmax('reverse',Y,PS)
  dx_dy = mapminmax('dx',X,Y,PS)
  dx_dy = mapminmax('dx',X,[],PS)
  name = mapminmax('name');
  fp = mapminmax('pdefaults');
  names = mapminmax('pnames');
  remconst('pcheck',FP);
  

Description

mapminmax processes matrices by normalizing the minimum and maximum values of each row to [YMIN, YMAX].

mapminmax(X,YMIN,YMAX) takes X and optional parameters

X	N x Q matrix or a 1 x TS row cell array of N x Q matrices
YMIN	Minimum value for each row of Y (default is -1)
YMAX	Maximum value for each row of Y (default is +1)

and returns

Y	Each M x Q matrix (where M == N) (optional)
PS	Process settings that allow consistent processing of values

mapminmax(X,FP) takes parameters as a struct: FP.ymin, FP.ymax.

mapminmax('apply',X,PS) returns Y, given X and settings PS.

mapminmax('reverse',Y,PS) returns X, given Y and settings PS.

mapminmax('dx',X,Y,PS) returns the M x N x Q derivative of Y with respect to X.

mapminmax('dx',X,[],PS) returns the derivative, less efficiently.

mapminmax('name') returns the name of this process method.

mapminmax('pdefaults') returns the default process parameter structure.

mapminmax('pdesc') returns the process parameter descriptions.

mapminmax('pcheck',FP) throws an error if any parameter is illegal.

Examples

Here is how to format a matrix so that the minimum and maximum values of each row are mapped to default interval [-1,+1].

• x1 = [1 2 4; 1 1 1; 3 2 2; 0 0 0]
  [y1,PS] = mapminmax(x1)
  

Next, apply the same processing settings to new values.

• x2 = [5 2 3; 1 1 1; 6 7 3; 0 0 0]
  y2 = mapminmax('apply',x2,PS)
  

Reverse the processing of y1 to get x1 again.

• x1_again = mapminmax('reverse',y1,PS)
  

Algorithm

It is assumed that X has only finite real values, and that the elements of each row are not all equal.

• y = (ymax-ymin)*(x-xmin)/(xmax-xmin) + ymin;
  

See Also

fixunknowns, mapstd, processpca

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