python - 来自缓冲区的 Numpy 二维数组？

Question

我有一个内存映射，其中包含一个二维数组，我想从中创建一个 numpy 数组。理想情况下，我想避免复制，因为涉及的数组可能很大。

我的代码如下所示:

n_bytes = 10000
tagname = "Some Tag from external System"
map = mmap.mmap(-1, n_bytes, tagname)
offsets = [0, 5000]

columns = []
for offset in offsets:
   #type and count vary in the real code, but for this dummy code I simply made them up. But I know the count and type for every column.
   np_type = np.dtype('f4')
   column_data = np.frombuffer(map, np_type, count=500, offset=offset)
   columns.append(column_data)

# this line seems to copy the data, which I would like to avoid
data = np.array(columns).T

Answer 1

假设您有一个字节数组并且您知道它的维度，那么答案非常简单。
想象一下缓冲区中图像的原始 RGB 数据(每像素 24 位)(名为“buff”)
尺寸为 1024x768

#read the buffer into 1D byte array
arr = numpy.frombuffer(buff, dtype=numpy.uint8)
#now shape the array as you please
arr.shape = (768,1024,3)