如何获得整个矩阵、数组或数据框的均值、中位数和其他统计数据? [英] How to get mean, median, and other statistics over entire matrix, array or dataframe?

问题描述

我知道这是一个基本问题，但由于某些奇怪的原因我无法找到答案.

I know this is a basic question but for some strange reason I am unable to find an answer.

我应该如何在整个数组、矩阵或数据框上应用基本的统计函数(如均值、中位数等)来获得唯一的答案，而不是行或列上的向量

How should I apply basic statistical functions like mean, median, etc. over entire array, matrix or dataframe to get unique answers and not a vector over rows or columns

推荐答案

由于这个问题有点多，我将更全面地处理这个问题，包括等".除了 mean 和 median.

Since this comes up a fair bit, I'm going to treat this a little more comprehensively, to include the 'etc.' piece in addition to mean and median.

1. 对于矩阵或数组，正如其他人所说，mean 和 median 将返回单个值.但是，var 将计算二维矩阵的列之间的协方差.有趣的是，对于多维数组，var 返回返回单个值.sd 在二维矩阵上可以工作，但已弃用，返回列的标准偏差.更好的是，mad 返回二维矩阵和多维数组上的单个值.如果您想要返回单个值，最安全的方法是首先使用 as.vector() 进行强制.玩得开心吗?

1. For a matrix, or array, as the others have stated, mean and median will return a single value. However, var will compute the covariances between the columns of a two dimensional matrix. Interestingly, for a multi-dimensional array, var goes back to returning a single value. sd on a 2-d matrix will work, but is deprecated, returning the standard deviation of the columns. Even better, mad returns a single value on a 2-d matrix and a multi-dimensional array. If you want a single value returned, the safest route is to coerce using as.vector() first. Having fun yet?

对于 data.frame，mean 已被弃用，但会再次单独作用于列.median 要求您先强制转换为向量，或者 unlist.和以前一样，var 将返回协方差，sd 再次被弃用，但将返回列的标准偏差.mad 要求您强制转换为向量或 unlist.一般来说，对于 data.frame，如果您想要对所有值进行操作，您通常只需 unlist 首先.

For a data.frame, mean is deprecated, but will again act on the columns separately. median requires that you coerce to a vector first, or unlist. As before, var will return the covariances, and sd is again deprecated but will return the standard deviation of the columns. mad requires that you coerce to a vector or unlist. In general for a data.frame if you want something to act on all values, you generally will just unlist it first.

最新突发新闻():在 R 3.0.0 mean.data.frame 已失效:

Late breaking news(): In R 3.0.0 mean.data.frame is defunctified:

o   mean() for data frames and sd() for data frames and matrices are
defunct.

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