Function reduce

pub fn reduce(
    src: &impl ToInputArray,
    dst: &mut impl ToOutputArray,
    dim: i32,
    rtype: i32,
    dtype: i32,
) -> Result<()>

Reduces a matrix to a vector.

The function reduce reduces the matrix to a vector by treating the matrix rows/columns as a set of 1D vectors and performing the specified operation on the vectors until a single row/column is obtained. For example, the function can be used to compute horizontal and vertical projections of a raster image. In case of REDUCE_MAX and #REDUCE_MIN, the output image should have the same type as the source one. In case of #REDUCE_SUM, REDUCE_SUM2 and #REDUCE_AVG, the output may have a larger element bit-depth to preserve accuracy. And multi-channel arrays are also supported in these two reduction modes.

The following code demonstrates its usage for a single channel matrix. example

And the following code demonstrates its usage for a two-channel matrix. example2

Parameters

• src: input 2D matrix.
• dst: output vector. Its size and type is defined by dim and dtype parameters.
• dim: dimension index along which the matrix is reduced. 0 means that the matrix is reduced to a single row. 1 means that the matrix is reduced to a single column.
• rtype: reduction operation that could be one of [reduce_types]
• dtype: when negative, the output vector will have the same type as the input matrix, otherwise, its type will be CV_MAKE_TYPE(CV_MAT_DEPTH(dtype), src.channels()).

See also

repeat, reduceArgMin, reduceArgMax

C++ default parameters

• dtype: -1