lapply函数来计算列表内数据帧的均值 [英] lapply function to compute means of data frames inside a list

问题描述

我正在尝试使用lapply函数来计算列表内数据帧的均值.

I am trying to compute means of data frames inside a list using lapply function.

df_list <- list(cars, mtcars)
sapply(df_list, mean)

上面的代码似乎无效.但是，当我将其更改为:

The above code doesn't seem to work. However when i changed it to:

 df_list <- c(cars, mtcars)
 sapply(df_list, mean)

输出具有两个数据帧的所有变量的均值.

The output had the means of all the variables of both data frames.

有一种方法可以使用第一种方法来计算均值.

is there a way to compute the means using the first approach.

推荐答案

使用purrr库来实现这一目标……要简单得多:

use the purrr library to achieve this...much simpler:

library(purrr) 
map(df_list, ~map_if(., is.numeric, mean))

如果您希望返回df，则:

If you want a df to be returned then:

map_df(df_list, ~map_if(., is.numeric, mean)) 

答案来自此处: 为什么map_if()在列表中不起作用 应归功于@Axeman

answer is from here: why does map_if() not work within a list credit should go to @Axeman

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