R中嵌套列表的直方图

Question

I have a nested list similar to this

df <- data.frame(width = c(1:5),height = c(1:5),depth = c(1:5))
list <- list(df,df*2,df*5,df*1.3)

I would like to make a histogram, in either base R or ggplot, of the final height of each list. I have tried

hist(tail(list[[1:4]]$height,1))

which yields

Error in list[[1:4]] : recursive indexing failed at level 3

as well as

for (i in 1:4){
hist(tail(list[[i]]$height,1))
}

which generates 4 separate histograms of a single observation. I am trying to avoid simply listing each observation in hist() like

hist(tail(list[[1]]$height,1),tail(list[[2]]$height,1),tail(list[[3]]$height,1))

because my actual data has many more than 4 sub-lists. How can I achieve this elegantly?

Answer 1

如果我们想提取 'height' 的最后一个元素，请使用sapply list ，提取（ $ ）列 'height'，获取tail值（ sapply - 此处返回一个vector ），然后应用hist

hist( sapply(list, function(x) tail(x$height, 1)))