将矩阵转换为列表

本文介绍了将矩阵转换为列表的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

假设我有一个矩阵foo，如下所示:

Suppose I have a matrix foo as follows:

foo <- cbind(c(1,2,3), c(15,16,17)) > foo [,1] [,2] [1,] 1 15 [2,] 2 16 [3,] 3 17

我想将其变成一个看起来像

I'd like to turn it into a list that looks like

[[1]] [1] 1 15 [[2]] [1] 2 16 [[3]] [1] 3 17

您可以按照以下步骤进行操作:

You can do it as follows:

lapply(apply(foo, 1, function(x) list(c(x[1], x[2]))), function(y) unlist(y))

我对没有那么复杂的替代方法感兴趣.请注意，如果您只是执行apply(foo, 1, function(x) list(c(x[1], x[2])))，它将返回列表中的一个列表，我希望避免这种情况.

I'm interested in an alternative method that isn't as complicated. Note, if you just do apply(foo, 1, function(x) list(c(x[1], x[2]))), it returns a list within a list, which I'm hoping to avoid.

推荐答案

这是一个更干净的解决方案:

Here's a cleaner solution:

as.list(data.frame(t(foo)))

这利用了一个事实，即数据帧实际上只是等长向量的列表(而矩阵实际上是一个显示有列和行的向量...您可以通过调用foo [5]来看到这一点) (例如).

That takes advantage of the fact that a data frame is really just a list of equal length vectors (while a matrix is really a vector that is displayed with columns and rows...you can see this by calling foo[5], for instance).

您也可以这样做，尽管并没有太大改善:

You could also do this, although it isn't much of an improvement:

lapply(1:nrow(foo), function(i) foo[i,])