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python Programming Glossary: a.itemsize

Is there a way to check if numpy arrays share the same data?

http://stackoverflow.com/questions/11286864/is-there-a-way-to-check-if-numpy-arrays-share-the-same-data

return np.concatenate element_offset x for x in range a.itemsize def share_memory a b Returns the number of shared bytes between..

test for membership in a 2d numpy array

http://stackoverflow.com/questions/16216078/test-for-membership-in-a-2d-numpy-array

as a 1 dimensional array of strings a a.ravel .view np.str a.itemsize a.shape 1 For example In 15 a np.array 1 2 2 3 1 3 In 16 a a.ravel.. In 15 a np.array 1 2 2 3 1 3 In 16 a a.ravel .view np.str a.itemsize a.shape 1 In 17 a.dtype Out 17 dtype ' S8' In 18 a.shape Out.. order 'C' b np.asarray b order 'C' a a.ravel .view np.str a.itemsize a.shape 1 b b.ravel .view np.str b.itemsize b.shape 1 return..

Fast Way to slice image into overlapping patches and merge patches to image

http://stackoverflow.com/questions/16774148/fast-way-to-slice-image-into-overlapping-patches-and-merge-patches-to-image

memory address. For example in a np.arange 10 .reshape 2 5 a.itemsize equals 4 ie 4 bytes or 32 bits for each element and a.strides..

Efficient Numpy 2D array construction from 1D array

http://stackoverflow.com/questions/4923617/efficient-numpy-2d-array-construction-from-1d-array

def rolling a window shape a.size window 1 window strides a.itemsize a.itemsize return np.lib.stride_tricks.as_strided a shape shape.. a window shape a.size window 1 window strides a.itemsize a.itemsize return np.lib.stride_tricks.as_strided a shape shape strides..

Using strides for an efficient moving average filter

http://stackoverflow.com/questions/4936620/using-strides-for-an-efficient-moving-average-filter

a shape a.size filtsize strides a.itemsize a.itemsize for i in range 0 filtsize 1 if i 0 b numpy.roll b.. a shape a.size filtsize strides a.itemsize a.itemsize for i in range 0 filtsize 1 if i 0 b numpy.roll b pow filtsize..

Numpy: Joining structured arrays?

http://stackoverflow.com/questions/5355744/numpy-joining-structured-arrays

def join_struct_arrays arrays sizes numpy.array a.itemsize for a in arrays offsets numpy.r_ 0 sizes.cumsum n len arrays..

Improve speed of reading and converting from binary file with python

http://stackoverflow.com/questions/5804052/improve-speed-of-reading-and-converting-from-binary-file-with-python

array.array 'h' a.fromfile open fn 'rb' os.path.getsize fn a.itemsize It is 40x times faster than struct.unpack from @samplebias's..

Using Numpy stride_tricks to get non-overlapping array blocks

http://stackoverflow.com/questions/8070349/using-numpy-stride-tricks-to-get-non-overlapping-array-blocks

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 sz a.itemsize h w a.shape bh bw 2 2 shape h bh w bw bh bw strides w sz sz.. 2 3 4 5 # 6 7 8 9 10 # 11 12 13 14 15 # 16 17 18 19 20 sz a.itemsize h w a.shape bh bw 2 2 shape h bh w bw bh bw print shape # 2.. blocks 0 0 0 1 is one item away. Since on my machine the a.itemsize is 4 bytes the stride is 1 4 4. This gives us the last value..