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python Programming Glossary: np.dotconvert rgb image to grayscale in python http://stackoverflow.com/questions/12201577/convert-rgb-image-to-grayscale-in-python import matplotlib.image as mpimg def rgb2gray rgb return np.dot rgb ... 3 0.299 0.587 0.144 img mpimg.imread 'image.png' gray..
Calculate camera world position with OpenCV Python http://stackoverflow.com/questions/14444433/calculate-camera-world-position-with-opencv-python the camera's position should be calculated like this x y z np.dot np.transpose rotation translation The coordinates I'm getting..
calling dot products and linear algebra operations in Cython? http://stackoverflow.com/questions/16114100/calling-dot-products-and-linear-algebra-operations-in-cython faster. Example functions I'd like to call dot product np.dot matrix inversion np.linalg.inv matrix multiplication taking..
Why is numpy's einsum faster than numpy's built in functions? http://stackoverflow.com/questions/18365073/why-is-numpys-einsum-faster-than-numpys-built-in-functions regardless of axes selection. The primary exception being np.dot as it calls DGEMM from a BLAS library. So why is np.einsum faster.. are equivalent The DGEMM case for completeness np.allclose np.dot arr_2D arr_2D np.einsum 'ij jk' arr_2D arr_2D True timeit np.einsum.. arr_2D arr_2D 10 loops best of 3 56.1 ms per loop timeit np.dot arr_2D arr_2D 100 loops best of 3 5.17 ms per loop The leading..
Speeding up a closest point on a hyperbolic paraboloid algorithm http://stackoverflow.com/questions/18858448/speeding-up-a-closest-point-on-a-hyperbolic-paraboloid-algorithm 0. 0. # Normalize segment and do edge tests ab ab AB test np.dot ac ab if test 0. return a AC 0. elif test AB return b BC 1... None while niter and error is None or error tol niter 1 u_ np.dot p_ v b a v c np.dot a v c a v c v_ np.dot p_ u a b u c np.dot.. error is None or error tol niter 1 u_ np.dot p_ v b a v c np.dot a v c a v c v_ np.dot p_ u a b u c np.dot b u c b u c error..
Inverse Distance Weighted (IDW) Interpolation with Python http://stackoverflow.com/questions/3104781/inverse-distance-weighted-idw-interpolation-with-python if weights is not None w weights ix # 0 w np.sum w wz np.dot w self.z ix if self.stat self.wn 1 self.wsum w interpol jinterpol..
Matrix and array multiplication in numpy http://stackoverflow.com/questions/3890621/matrix-and-array-multiplication-in-numpy numpy as np x np.arange 9 .reshape 3 3 y np.arange 3 print np.dot x y Or in newer versions of numpy simply use x.dot y Personally..
What are the differences between numpy arrays and matrices? Which one should I use? http://stackoverflow.com/questions/4151128/what-are-the-differences-between-numpy-arrays-and-matrices-which-one-should-i-u 6 4 To obtain the result of matrix multiplication you use np.dot print np.dot c d # 13 20 # 5 8 The operator also behaves differently.. the result of matrix multiplication you use np.dot print np.dot c d # 13 20 # 5 8 The operator also behaves differently print..
Fast tensor rotation with NumPy http://stackoverflow.com/questions/4962606/fast-tensor-rotation-with-numpy can still make it two times faster def rotT T gggg return np.dot gggg.transpose 1 3 5 7 0 2 4 6 .reshape 81 81 T.reshape 81..
http://stackoverflow.com/questions/5073767/how-can-i-efficiently-process-a-numpy-array-in-blocks-similar-to-matlabs-blkpro B 1 1 # 14 15 # 20 21 # for preserving original shape B np.dot B np.array 0 1 1 0 print A # 1 0 3 2 5 4 # 7 6 9 8 11 10 # .....
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