void NDMask::MaskSection(const std::vector<size_t>& sectionOffset, const NDShape& sectionShape)
{
// TODO: Implement batching of masking operation for masks residing on GPUs to avoid making
// GPU invocations for each MaskSection call.
if (sectionOffset.size() > m_maskShape.NumAxes())
LogicError("NDMask::MaskSection: The sectionOffset cannot have dimensionality higher than the number of axes of 'this' mask");
if (sectionShape.NumAxes() > m_maskShape.NumAxes())
LogicError("NDMask::MaskSection: The section shape cannot have an axes count higher than the number of axes of 'this' mask");
std::vector<size_t> offset(m_maskShape.NumAxes(), 0);
for (size_t i = 0; i < sectionOffset.size(); ++i)
offset[i] = sectionOffset[i];
NDShape shape = sectionShape.AppendShape(NDShape(m_maskShape.NumAxes() - sectionShape.NumAxes(), NDShape::InferredDimension));
auto maskMatrix = GetMatrix();
size_t rowOffset = offset[0];
size_t colOffset = offset[1];
size_t sliceRowLength = (shape[0] != NDShape::InferredDimension) ? shape[0] : (maskMatrix->GetNumRows() - rowOffset);
size_t sliceColLength = (shape[1] != NDShape::InferredDimension) ? shape[1] : (maskMatrix->GetNumCols() - colOffset);
if ((rowOffset == 0) && (sliceRowLength == maskMatrix->GetNumRows()))
maskMatrix->ColumnSlice(colOffset, sliceColLength).SetValue(0);
else
{
// Since Matrix does not support strides in the row dimension, we will need to create separate slices for each column
for (size_t i = colOffset; i < (colOffset + sliceColLength); ++i)
{
auto column = maskMatrix->ColumnSlice(i, 1);
column.Reshape(1, maskMatrix->GetNumRows());
column.ColumnSlice(rowOffset, sliceRowLength).SetValue(0);
}
}
}
NDMask::NDMask(const NDShape& shape, const DeviceDescriptor& device/* = DeviceDescriptor::DefaultDevice()*/)
: NDMask(shape, AllocateMatrix(shape, device))
{
if (shape.NumAxes() > 2)
LogicError("NDMask instances with more than 2 axes are currently unsupported");
Clear();
}