2021-08-04

利用Numpy分割矩阵

应用场景：滑动窗口计算

import numpy as np
import re

def window(array, width, height):
    """
    将array分割成若干小窗口
    """
    # 判断是否符合条件
    _rowCount, _colCount = array.shape
    if _rowCount % height or _colCount % width:
        raise ValueError('please input suitable width/height value')
    # 计算最终生成shape
    rowCount, colCount = int(_rowCount / height), int(_colCount / width)
    # 字节数
    bytesN = int(int(re.match('[a-zA-Z]+(\d+)', str(array.dtype)).group(1)) / 8)
    # 生成目标矩阵
    target = np.lib.stride_tricks.as_strided(array, shape=(rowCount, colCount, height, width), strides=(height * _colCount * bytesN, width * bytesN, *array.strides))
    print(target)
    return target

window(np.array([i for i in range(1, 82)]).reshape(9, 9) / 1.0, 3, 3)

运行结果

[[[[ 1.  2.  3.]
   [10. 11. 12.]
   [19. 20. 21.]]

  [[ 4.  5.  6.]
   [13. 14. 15.]
   [22. 23. 24.]]

  [[ 7.  8.  9.]
   [16. 17. 18.]
   [25. 26. 27.]]]


 [[[28. 29. 30.]
   [37. 38. 39.]
   [46. 47. 48.]]

  [[31. 32. 33.]
   [40. 41. 42.]
   [49. 50. 51.]]

  [[34. 35. 36.]
   [43. 44. 45.]
   [52. 53. 54.]]]


 [[[55. 56. 57.]
   [64. 65. 66.]
   [73. 74. 75.]]

  [[58. 59. 60.]
   [67. 68. 69.]
   [76. 77. 78.]]

  [[61. 62. 63.]
   [70. 71. 72.]
   [79. 80. 81.]]]]

标签：04,rowCount,int,08,height,width,colCount,2021,array
来源： https://blog.csdn.net/weixin_44092702/article/details/120750091