.. meta::
    :description: Code snippets pad ROI Numpy array

How to pad a ROI
================

In this example, we copy a slice of a source ROI into different slices of a destination ROI,
in order to pad a few slices at the lower Z and at the higher Z.

The source ROI is named ``sourceROI``::

    # Creating the destination ROI
    destinationROI = sourceROI.copy()

    # Adapting the shape of the destination ROI to contain the padding slices
    countPaddingSlicesOnEachSide = 10
    originalZSize = sourceROI.getZSize()
    destinationROIZSize = originalZSize + 2*countPaddingSlicesOnEachSide
    destinationROI.setZSize(destinationROIZSize)
    destinationROIBox = destinationROI.getBox()
    destinationROIDirection2 = destinationROIBox.getDirection2()
    destinationROISpacingDirection2 = destinationROIBox.getDirection2Spacing()
    destinationROIOrigin = destinationROIBox.getOrigin()
    destinationROINewOrigin = destinationROIOrigin - countPaddingSlicesOnEachSide*destinationROISpacingDirection2*destinationROIDirection2
    destinationROIBox.setOrigin(destinationROINewOrigin)
    destinationROI.setBox(destinationROIBox)
    destinationROI.clear()

    timeStep = 0

    # Copying common region data
    # The method addROI uses a projection when the shape of the destination is not the same as the source
    destinationROI.addROI(sourceROI)

    # Padding at lower Z
    # Getting the source data
    tempROILowerZ = sourceROI.getSubset(0, 0, 0, timeStep, sourceROI.getXSize()-1, sourceROI.getYSize()-1, 0, timeStep, None, None)

    # Copying the source data in all the padding slices
    from ORSModel import Vector3
    for zIndex in range(countPaddingSlicesOnEachSide):
        # Getting the coordinates of the origin to set in tempROILowerZ, to align tempROILowerZ with the padding slice to write
        originToSet = destinationROI.getVoxelToWorldCoordinates(Vector3(0, 0, zIndex))
        tempROILowerZ.setOrigin(originToSet)
        destinationROI.addROI(tempROILowerZ)

    tempROILowerZ.deleteObject()

    # Padding at higher Z
    tempROIHigherZ = sourceROI.getSubset(0, 0, originalZSize-1, timeStep, sourceROI.getXSize()-1, sourceROI.getYSize()-1, originalZSize-1, timeStep, None, None)
    for zIndex in range(countPaddingSlicesOnEachSide):
        originToSet = destinationROI.getVoxelToWorldCoordinates(Vector3(0, 0, destinationROIZSize-1-zIndex))
        tempROIHigherZ.setOrigin(originToSet)
        destinationROI.addROI(tempROIHigherZ)

    tempROIHigherZ.deleteObject()

    # Setting the properties of the new ROI
    destinationROI.setTitle(sourceROI.getTitle() + ' (Padded)')

    # Publishing the new object
    destinationROI.publish()