提取矩陣

Question

我有以下形式的列表：

x = replicate(3, list(m = matrix(rnorm(16), 4, 4), s = rnorm(1)), simplify=FALSE) 
x 
#[[1]] 
#[[1]]$m 
#   [,1]  [,2]  [,3]  [,4] 
#[1,] -0.412209 -0.50227 -2.62340 0.17549 
#[2,] 1.344723 -1.52060 -0.59093 1.19701 
#[3,] -0.016289 -0.88286 -0.33307 -0.48351 
#[4,] 0.060760 0.32131 1.16896 -0.45940 
# 
#[[1]]$s 
#[1] -1.3588 
# 
# 
#[[2]] 
#[[2]]$m 
#   [,1]  [,2]  [,3] [,4] 
#[1,] -0.15345 -0.82106 0.93839 1.46115 
#[2,] 1.60950 -2.35833 0.89621 0.35542 
#[3,] -0.17792 0.54444 -0.17414 0.63614 
#[4,] 0.85038 0.84373 0.24687 0.60172 
# 
#[[2]]$s 
#[1] 3.6597 
# 
# 
#[[3]] 
#[[3]]$m 
#   [,1]  [,2]  [,3]  [,4] 
#[1,] 1.27724 0.19397 0.47393 -0.66518 
#[2,] -0.75244 1.16476 1.74843 -1.03732 
#[3,] 0.99433 -1.06129 0.15674 -0.83856 
#[4,] 0.18471 1.30852 -0.38024 0.88538 
# 
#[[3]]$s 
#[1] 0.49526 

的目標是從列表中獲得上述矩陣的列表，並且同樣地標量的向量。如何才能做到這一點？謝謝！

Answer 1

你的意思是這樣的...？

sapply(x, '[', 'm')   # List of matrices 
unlist(sapply(x, '[', 's')) # Vector of scalars