84 lines
2.7 KiB
Python
84 lines
2.7 KiB
Python
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##
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# This software was developed and / or modified by Raytheon Company,
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# pursuant to Contract DG133W-05-CQ-1067 with the US Government.
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#
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# U.S. EXPORT CONTROLLED TECHNICAL DATA
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# This software product contains export-restricted data whose
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# export/transfer/disclosure is restricted by U.S. law. Dissemination
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# to non-U.S. persons whether in the United States or abroad requires
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# an export license or other authorization.
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#
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# Contractor Name: Raytheon Company
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# Contractor Address: 6825 Pine Street, Suite 340
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# Mail Stop B8
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# Omaha, NE 68106
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# 402.291.0100
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#
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# See the AWIPS II Master Rights File ("Master Rights File.pdf") for
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# further licensing information.
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###
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from numpy import sqrt
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from numpy import shape
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from numpy import empty
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from numpy import hypot
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from numpy import where
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from numpy import NaN
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import Vector as Vector
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##
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# Calculate the deformation components of Vector.
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#
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# @param Vector: A tuple(U,V) of numpy arrays. U and V must be the same size,
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# at least 2d, and at least 3x3 in the first two dimensions.
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# @param dx: The spacing between data points in the X direction (array or scalar)
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# @param dy: The spacing between data points in the Y direction (array or scalar)
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# @return: The deformation array of Vector.
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def execute(U, V, dx, dy):
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# create an empty array the same dimensions as U
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resultx = empty(U.shape, U.dtype)
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resulty = empty(U.shape, U.dtype)
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# flag edges as invalid
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resultx[0,:] = NaN
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resultx[-1,:] = NaN
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resultx[1:-1,0] = NaN
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resultx[1:-1,-1] = NaN
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resulty[0,:] = NaN
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resulty[-1,:] = NaN
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resulty[1:-1,0] = NaN
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resulty[1:-1,-1] = NaN
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# strip off edges of dx if it's not a scalar
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shapedx = shape(dx)
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if len(shapedx) < sum(shapedx):
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dx = dx[1:-1,1:-1]
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# strip off edges of dy if it's not a scalar
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shapedy = shape(dy)
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if len(shapedy) < sum(shapedy):
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dy = dy[1:-1,1:-1]
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# Calculate deformation vector components.
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qqq = 0.5/dx
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www = 0.5/dy
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dst = (U[1:-1,0:-2] - U[1:-1,2:]) * qqq
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dst += (V[0:-2,1:-1] - V[2:,1:-1]) * www
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dsh = (U[0:-2,1:-1] - U[2:,1:-1]) * qqq
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dsh += (V[1:-1,2:] - V[1:-1,0:-2]) * www
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qqq = dst*dst + dsh*dsh
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www = sqrt(qqq)
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ans = sqrt((qqq+www*dst)/2)
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Q = where(ans != 0.0, www*dsh/(2*ans), www)
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# put ans in the valid block of result
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resultx[1:-1,1:-1] = Q
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resulty[1:-1,1:-1] = ans
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return Vector.execute(resultx,resulty)
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