连接具有不同形状复制值的数组

Question

我有一个形状:(15,2)的数组。我还有另一个数组值:[0, 3, 5].

我想在第一个数组中创建另一个列，其值来自第二个数组，其中前5行值为0，第6-10行值为3，最后5行值为5。

一样:

[0,
0,
0,
0,
0,
3,
3,
3,
3,
3,
5,
5,
5,
5,
5]

是否有任何numpy方法可以做到这一点?

谢谢!

Answer 1

您可以使用numpy的内置repeat和stack:

a = np.zeros((15,2))
b = np.array([0,3,5])
np.hstack((a, np.repeat(b,5)[:,None]))

输出:

[[0. 0. 0.]
[0. 0. 0.]
[0. 0. 0.]
[0. 0. 0.]
[0. 0. 0.]
[0. 0. 3.]
[0. 0. 3.]
[0. 0. 3.]
[0. 0. 3.]
[0. 0. 3.]
[0. 0. 5.]
[0. 0. 5.]
[0. 0. 5.]
[0. 0. 5.]
[0. 0. 5.]]

Answer 2

rand = np.random.random((15,2)) # shape is (15,2)
vals = np.array([0,3,5]) # shape is (3,)
res = np.concatenate(([np.full((rand.shape[0]//vals.shape[0],), val) for val in vals]), axis=0)
res

输出:

array([0, 0, 0, 0, 0, 3, 3, 3, 3, 3, 5, 5, 5, 5, 5])

最后,

final = np.hstack((rand, res.reshape(15,1)))
final

输出:

array([[0.29759807, 0.60548479, 0.        ],
[0.61242249, 0.46456274, 0.        ],
[0.86172011, 0.2963868 , 0.        ],
[0.91728575, 0.36366023, 0.        ],
[0.56488556, 0.82130321, 0.        ],
[0.59482141, 0.46148353, 3.        ],
[0.7762271 , 0.25415058, 3.        ],
[0.09176551, 0.9687253 , 3.        ],
[0.06473259, 0.34686598, 3.        ],
[0.69542414, 0.15540001, 3.        ],
[0.02880707, 0.23169327, 5.        ],
[0.90004256, 0.22145591, 5.        ],
[0.61596969, 0.46807342, 5.        ],
[0.02263769, 0.68522023, 5.        ],
[0.81777274, 0.58145853, 5.        ]])

Answer 3

使用np.concatenate.

• 将第二个数组转换为2d"矢量";数组，每行有1列

a = [0, 0, 0, 0, 0, 3, 3, 3, 3, 3, 5, 5, 5, 5, 5] # your list of [0, 3, 5]
a = np.array([a]).T # [ [0], [0], [0], ..., [5] ] the "vector" array

那么简单

b = np.array([[i, i +1] for i in range(15)]) # some example 15x2 array
print(np.concatenate((b, a), axis=1)) 

输出为

array([[ 0,  1,  0],
[ 1,  2,  0],
[ 2,  3,  0],
[ 3,  4,  0],
[ 4,  5,  0],
[ 5,  6,  3],
[ 6,  7,  3],
[ 7,  8,  3],
[ 8,  9,  3],
[ 9, 10,  3],
[10, 11,  5],
[11, 12,  5],
[12, 13,  5],
[13, 14,  5],
[14, 15,  5]])