Covariation flags.
| Enumerator | |
|---|---|
| COVAR_SCRAMBLED Python: cv.COVAR_SCRAMBLED | The output covariance matrix is calculated as: \[\texttt{scale} \cdot [ \texttt{vects} [0]- \texttt{mean} , \texttt{vects} [1]- \texttt{mean} ,...]^T \cdot [ \texttt{vects} [0]- \texttt{mean} , \texttt{vects} [1]- \texttt{mean} ,...],\] The covariance matrix will be nsamples x nsamples. Such an unusual covariance matrix is used for fast PCA of a set of very large vectors (see, for example, the EigenFaces technique for face recognition). Eigenvalues of this "scrambled" matrix match the eigenvalues of the true covariance matrix. The "true" eigenvectors can be easily calculated from the eigenvectors of the "scrambled" covariance matrix. |
| COVAR_NORMAL Python: cv.COVAR_NORMAL | The output covariance matrix is calculated as: \[\texttt{scale} \cdot [ \texttt{vects} [0]- \texttt{mean} , \texttt{vects} [1]- \texttt{mean} ,...] \cdot [ \texttt{vects} [0]- \texttt{mean} , \texttt{vects} [1]- \texttt{mean} ,...]^T,\] covar will be a square matrix of the same size as the total number of elements in each input vector. One and only one of COVAR_SCRAMBLED and COVAR_NORMAL must be specified. |
| COVAR_USE_AVG Python: cv.COVAR_USE_AVG | If the flag is specified, the function does not calculate mean from the input vectors but, instead, uses the passed mean vector. This is useful if mean has been pre-calculated or known in advance, or if the covariance matrix is calculated by parts. In this case, mean is not a mean vector of the input sub-set of vectors but rather the mean vector of the whole set. |
| COVAR_SCALE Python: cv.COVAR_SCALE | If the flag is specified, the covariance matrix is scaled. In the "normal" mode, scale is 1./nsamples . In the "scrambled" mode, scale is the reciprocal of the total number of elements in each input vector. By default (if the flag is not specified), the covariance matrix is not scaled ( scale=1 ). |
| COVAR_ROWS Python: cv.COVAR_ROWS | If the flag is specified, all the input vectors are stored as rows of the samples matrix. mean should be a single-row vector in this case. |
| COVAR_COLS Python: cv.COVAR_COLS | If the flag is specified, all the input vectors are stored as columns of the samples matrix. mean should be a single-column vector in this case. |
k-Means flags
| Enumerator | |
|---|---|
| KMEANS_RANDOM_CENTERS Python: cv.KMEANS_RANDOM_CENTERS | Select random initial centers in each attempt. |
| KMEANS_PP_CENTERS Python: cv.KMEANS_PP_CENTERS | Use kmeans++ center initialization by Arthur and Vassilvitskii [Arthur2007]. |
| KMEANS_USE_INITIAL_LABELS Python: cv.KMEANS_USE_INITIAL_LABELS | During the first (and possibly the only) attempt, use the user-supplied labels instead of computing them from the initial centers. For the second and further attempts, use the random or semi-random centers. Use one of KMEANS_*_CENTERS flag to specify the exact method. |
| Enumerator | |
|---|---|
| REDUCE_SUM Python: cv.REDUCE_SUM | the output is the sum of all rows/columns of the matrix. |
| REDUCE_AVG Python: cv.REDUCE_AVG | the output is the mean vector of all rows/columns of the matrix. |
| REDUCE_MAX Python: cv.REDUCE_MAX | the output is the maximum (column/row-wise) of all rows/columns of the matrix. |
| REDUCE_MIN Python: cv.REDUCE_MIN | the output is the minimum (column/row-wise) of all rows/columns of the matrix. |
V is a 3-element vector with member fields x, y and z.
Swaps two matrices.