我想创造出具有向下运行对角线2D模式稀疏矩阵。 这可能是最简单的用一个简单的例子来解释。
说我的模式是：[1,0,2,0,1] ...
我想创建一个稀疏矩阵：
[[2,0,1,0,0,0,0...0],
[0,2,0,1,0,0,0...0],
[1,0,2,0,1,0,0...0],
[0,1,0,2,0,1,0...0],
[0,0,1,0,2,0,1...0],
[...]]
该scipy.sparse.dia_matrix似乎是一个不错的人选，但是，我根本无法弄清楚如何完成我从提供的文档需要。 先感谢您
N = 10
diag = np.zeros(N) + 2
udiag = np.zeros(N) + 1
ldiag = np.zeros(N) + 1
mat = scipy.sparse.dia_matrix(([diag, udiag, ldiag], [0, 2, -2]), shape=(N, N))
print mat.todense()
[[ 2. 0. 1. 0. 0. 0. 0. 0. 0. 0.]
[ 0. 2. 0. 1. 0. 0. 0. 0. 0. 0.]
[ 1. 0. 2. 0. 1. 0. 0. 0. 0. 0.]
[ 0. 1. 0. 2. 0. 1. 0. 0. 0. 0.]
[ 0. 0. 1. 0. 2. 0. 1. 0. 0. 0.]
[ 0. 0. 0. 1. 0. 2. 0. 1. 0. 0.]
[ 0. 0. 0. 0. 1. 0. 2. 0. 1. 0.]
[ 0. 0. 0. 0. 0. 1. 0. 2. 0. 1.]
[ 0. 0. 0. 0. 0. 0. 1. 0. 2. 0.]
[ 0. 0. 0. 0. 0. 0. 0. 1. 0. 2.]]
下面是创建这样一个列表的列表一个有趣的方法：
>>> n = 7
>>> a = n*[0] + [1, 0, 2, 0, 1] + [0]*n
>>> [a[-i+n+2:-i+2*n+2] for i in xrange(n)]
[[2, 0, 1, 0, 0, 0, 0],
[0, 2, 0, 1, 0, 0, 0],
[1, 0, 2, 0, 1, 0, 0],
[0, 1, 0, 2, 0, 1, 0],
[0, 0, 1, 0, 2, 0, 1],
[0, 0, 0, 1, 0, 2, 0],
[0, 0, 0, 0, 1, 0, 2]]
In [27]: N = 5
In [28]: diagonalvals = [7, 8, 9]
In [29]: offsets = [-2, 0, 2]
In [30]: diagonaldata = [[v for n in range(N)] for v in diagonalvals]
In [31]: print diagonaldata
[[7, 7, 7, 7, 7], [8, 8, 8, 8, 8], [9, 9, 9, 9, 9]]
In [32]: A = scipy.sparse.dia_matrix((diagonaldata, offsets), shape=(N, N))
In [33]: print A
(2, 0) 7
(3, 1) 7
(4, 2) 7
(0, 0) 8
(1, 1) 8
(2, 2) 8
(3, 3) 8
(4, 4) 8
(0, 2) 9
(1, 3) 9
(2, 4) 9
