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[英]How to make a 2d numpy array from an empty numpy array by adding 1d numpy arrays?
[英]How to make a numpy array from an array of arrays?
我在ipython3
实验,在那里我创建了一个数组数组:
In [105]: counts_array
Out[105]:
array([array([ 17, 59, 320, ..., 1, 7, 0], dtype=uint32),
array([ 30, 71, 390, ..., 12, 20, 6], dtype=uint32),
array([ 7, 145, 214, ..., 4, 12, 0], dtype=uint32),
array([ 23, 346, 381, ..., 15, 19, 5], dtype=uint32),
array([ 51, 78, 270, ..., 3, 0, 2], dtype=uint32),
array([212, 149, 511, ..., 19, 31, 8], dtype=uint32)], dtype=object)
In [106]: counts_array.shape
Out[106]: (6,)
In [107]: counts_array[0].shape
Out[107]: (1590,)
我想从我创建的这个怪物中获得一个普通的shape=(6, 1590), dtype=uint32
数组。
我怎样才能做到这一点?
你可以使用np.vstack
-
np.vstack(counts_array)
使用np.concatenate
另一种方法 -
np.concatenate(counts_array).reshape(len(counts_array),-1)
样品运行 -
In [23]: a
Out[23]:
array([array([68, 92, 84, 35, 14, 71, 55, 40, 21, 41]),
array([30, 90, 52, 64, 86, 68, 61, 85, 26, 98]),
array([98, 64, 23, 49, 13, 17, 52, 96, 97, 19]),
array([54, 26, 25, 22, 95, 77, 20, 73, 22, 80]),
array([15, 84, 91, 54, 25, 21, 37, 19, 25, 25]),
array([87, 17, 49, 74, 11, 34, 27, 23, 22, 83])], dtype=object)
In [24]: np.vstack(a)
Out[24]:
array([[68, 92, 84, 35, 14, 71, 55, 40, 21, 41],
[30, 90, 52, 64, 86, 68, 61, 85, 26, 98],
[98, 64, 23, 49, 13, 17, 52, 96, 97, 19],
[54, 26, 25, 22, 95, 77, 20, 73, 22, 80],
[15, 84, 91, 54, 25, 21, 37, 19, 25, 25],
[87, 17, 49, 74, 11, 34, 27, 23, 22, 83]])
经过各种实验,结果证明以下简单语法正常:
numpy.array([sub_array for sub_array in counts_array])
我的第一个工作版本不必要复杂:
numpy.array([[*sub_array] for sub_array in counts_array], dtype=numpy.uint32)
你考虑过numpy.vstack()
吗? 我经常使用它进行这种操作。
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