Scale: Difference between revisions
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===Purpose=== | ===Purpose=== | ||
Scales data using specified means and | Scales data using specified means and standard deviations. | ||
===Synopsis=== | ===Synopsis=== | ||
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sx = scale(x,means) subtracts a vector means from a matrix x and returns the result as sx. If means is the vector of means this routine mean centers x. | sx = scale(x,means) subtracts a vector means from a matrix x and returns the result as sx. If means is the vector of means this routine mean centers x. | ||
sx = scale(x,means,''stds'') subtracts a vector means from a matrix x, divides each column by the corresponding element in the vector ''stds'' and returns the result as sx. If means is the vector of means and ''stds'' is the vector of standard deviations this routine | sx = scale(x,means,''stds'') subtracts a vector means from a matrix x, divides each column by the corresponding element in the vector ''stds'' and returns the result as sx. If means is the vector of means and ''stds'' is the vector of standard deviations this routine auto-scales x so that each column of sx has zero mean and unit variance. | ||
The optional input (options) is defined below. | |||
===Options=== | |||
The optional input options is an options structure | The optional input (options) is an options structure containing: | ||
* '''stdthreshold''': <tt>[0]</tt> scalar value or vector of standard deviation threshold values. If a standard deviation is below its corresponding threshold value, the threshold value will be used in lieu of the actual value. A scalar value is used as a threshold for all variables. | |||
===See Also=== | ===See Also=== | ||
[[auto]], [[gscaler]], [[medcn]], [[mncn]], [[npreprocess]], [[preprocess]], [[rescale]] | [[auto]], [[gscaler]], [[medcn]], [[mncn]], [[npreprocess]], [[preprocess]], [[rescale]] | ||
Revision as of 12:00, 7 October 2008
Purpose
Scales data using specified means and standard deviations.
Synopsis
- sx = scale(x,means,stds,options)
Description
sx = scale(x,means) subtracts a vector means from a matrix x and returns the result as sx. If means is the vector of means this routine mean centers x.
sx = scale(x,means,stds) subtracts a vector means from a matrix x, divides each column by the corresponding element in the vector stds and returns the result as sx. If means is the vector of means and stds is the vector of standard deviations this routine auto-scales x so that each column of sx has zero mean and unit variance.
The optional input (options) is defined below.
Options
The optional input (options) is an options structure containing:
- stdthreshold: [0] scalar value or vector of standard deviation threshold values. If a standard deviation is below its corresponding threshold value, the threshold value will be used in lieu of the actual value. A scalar value is used as a threshold for all variables.
See Also
auto, gscaler, medcn, mncn, npreprocess, preprocess, rescale