我有一个元组列表list1
list1 = [[('a',0.01),('b',0.23),('c',1e-7)],
[('a',0.91),('b',0.067),('c',0.38)]]
我想创建一个numpy矩阵,其中每一行都是list1
中元组的第二个值。所以矩阵,我们称之为A
,将形成
A = [[0.01,0.23,1e-7],[0.91,0.067,0.38]]
A.shape
>>> (2,3)
到目前为止,我已经设法以缓慢而低效的方式实现这一目标
A = []
for i in range(len(list1)):
A.append(np.array([v for k,v in list1[i]]))
A = np.array(A)
如何使用列表理解来完成此操作?
答案 0 :(得分:5)
您需要嵌套列表推导:
np.array([[tup[1] for tup in lst] for lst in list1])
Out:
array([[ 1.00000000e-02, 2.30000000e-01, 1.00000000e-07],
[ 9.10000000e-01, 6.70000000e-02, 3.80000000e-01]])
更好的解决方案是:
np.array(list1)[:,:,1].astype('float')
Out:
array([[ 1.00000000e-02, 2.30000000e-01, 1.00000000e-07],
[ 9.10000000e-01, 6.70000000e-02, 3.80000000e-01]])