Covmatrix object (Multivariate Analysis Toolbox for Matlab®)

This object represents the covariance matrix (or correlation) between variables. It inherits from the parent object vvmatrix.

Navigate to:     General Description     Class Structure     Class Construction     Class Functions

Each field can be accessed by the dot (.) operation, or by the GET function. The GET function can work on multiple instances simultaneously. Most fields, except for those that are Dependent, can be modified using the dot (.) operation, or by the SET function.

		Field	Description	Type	Default	Dedicated Get/Set Function
		vv_type	type of data, either 'covariance' or 'correlation'	string	''
		corr_type	type of correlation, either 'pearson', 'spearman', or 'kendall'	string	''
		pval	p-value for the test whether rho = 0	double matrix of the same dimensions as the field matrix<\i>	[]
		sample_size	sample size used to compute the correlation/covariance	integer matrix of the same dimensions as the field matrix<\i>	[]
		type	Inherited from vvmatrix. Type of matrix. It is always 'variable-variable'	string	'variable-variable'
		row_units	Inherited from vvmatrix. units of the row-variables.	cell	{}
		row_level	Inherited from vvmatrix. level of the row-variables. Can be nominal/ordinal/numerical/unknown	cell	{}
		col_units	Inherited from vvmatrix. units of the column-variables.	cell	{}
		col_level	Inherited from vvmatrix. level of the column-variables. Can be nominal/ordinal/numerical/unknown	cell	{}
		is_square	Inherited from vvmatrix. true if the row-variables are identical to the column-variable.	logical	false
		name	Inherited from datamatrix. name of object, should be short and used as identifier. This field will never be empty.	string	'unnamed'
		description	Inherited from datamatrix. verbal description of the class content.	string	''
		source	Inherited from datamatrix. verbal description of the source of information.	string	''
		row_name	Inherited from datamatrix. Name of the row-category (for example, in gene arrays it can be "tissue").	string	''
		row_sampleset	Inherited from datamatrix. A sampleset describing the row-samples.	sampleset	[]
		row_groupings	Inherited from datamatrix. grouping objects associated with the row-samples.	grouping array	[]
		col_name	Inherited from datamatrix. Name of the column-category (for example, in gene arrays it can be "genes").	string	''
		col_sampleset	Inherited from datamatrix. A sampleset describing the column-samples.	sampleset	[]
		col_groupings	Inherited from datamatrix. grouping objects associated with the column-samples.	grouping array	[]
		matrix	Inherited from datamatrix. the data matrix.	double	[]
		transformations	Inherited from datamatrix. keeping track on transformations that had been applied previously on the matrix.	structure	[]
	Dependent	no_rows	Inherited from datamatrix. number of row-samples.	integer scalar	0	norows
	Dependent	no_cols	Inherited from datamatrix. number of column-samples.	integer scalar	0	nocols

Empty instance (scalar)

an empty covmatrix instance, with all fields initialized to their default values.

syntax: cvm = covmatrix;

Empty instance (matrix)

an array of empty covmatrix instances.

syntax: cvm = covmatrix(size,'size');

Copy constructor

one covmatrix instance is copied into another.

syntax: cvm_destination = covmatrix(cvm_origin);

Construction by field names

an instance is formed by directly providing field values. Any field which is not dependent is permitted.

syntax: cvm = covmatrix(field_name, field_value, ...);

Reading-in a matrix

an instance is formed by reading-in an externally provided matrix.

syntax: cvm = covmatrix(matrix);

Display:

show

displays class content. Source: datamatrix.

I/O functions:

xlswrite

writes VVMATRIX data into an excel sheet. Source: vvmatrix.

Inference:

ci

computes confidence intervals for the correlation values.

dependentvariables

reports pairs that are significantly dependent.

testindependence

computes p_values for the independence test.

Information extraction:

colid

finds the IDs of a list of column-variables. Source: datamatrix.

rowid

finds the IDs of a list of row-variables. Source: datamatrix.

SET/GET functions:

colnames

retrieves the column-variable names. Source: datamatrix.

get

get method

matrix

retrieves the variable-by-variable matrix. Source: vvmatrix.

nocols

retrieves the number of columns in DATAMATRIX instances. Source: datamatrix.

norows

retrieves the number of rows in DATAMATRIX instances. Source: datamatrix.

rownames

retrieves the row-variable names. Source: datamatrix.

set

set method

Transformations:

deletecols

eliminate col-variables from a COVMATRIX instance.

deleterows

eliminate row-variables from a COVMATRIX instance.

deletevariables

eliminate the same variables from the rows and columns.

Visualization:

plot

plots the covariance/correlation matrix