将表列表更改为R中的data.frame [英] Changing a list of tables to a data.frame in R

问题描述

下面，我首先查找变量X和Y是否具有重复少于4次的值.我在low中找到并列出了这些值.

Below, I first find if variables X and Y have a value that is repeated less than 4 times. I find and list these values in low.

我想知道如何使用BASE R将table列表的low转换为如下所示的我想要的输出?

I wonder, using BASE R, how can I transform low which is a list of tables to my desired output shown below?

注意: 下面的数据是玩具，请提供功能性答案.

Note: The data below is toy, a functional answer is appreciated.

data <- data.frame(id = c(rep("AA",4), rep("BB",2), rep("CC",2)), X = c(1,1,1,1,1,1,3,3), 
                                                                  Y = c(9,9,9,7,6,6,6,6),
                                                                  Z = 1:8)
mods <- c("X","Y")
A <- setNames(lapply(seq_along(mods), function(i) table(data[[mods[i]]], dnn = NULL)), mods)

low <- setNames(lapply(seq_along(A), function(i) A[[i]][which(A[[i]] < 4)]), names(A))

所需的输出:

data.frame(id = c("CC", "AA", "AA"), value = c(3, 7, 9), var.name = c("X", "Y", "Y"), occur = c(2, 1, 3))

#   id value var.name occur     # `value` comes from the `names(low[[i]])`# i = 1,2                                 
# 1 CC     3        X     2     # `occur` comes from `as.numeric(low[[i]])`
# 2 AA     7        Y     1
# 3 AA     9        Y     3

推荐答案

我们用'id'拆分'data'的列子集，用lapply遍历list，用和table的相应stack ed'low'list，Filter删除具有行数0或length 0的元素以创建"lst1".在"lst1"中，使用元素Map和rbind在内部names和外部names中创建其他列

We split the subset of columns of 'data' with 'id', loop through the list with lapply, do an inner join with merge with the corresponding stacked 'low' list of tables, Filter out the elements that are having number of rows 0 or length 0 to create 'lst1'. From 'lst1', create additional columns from the inner and outer names with Map and rbind the elements

lst1 <- Filter(length, lapply(split(data[c('X', 'Y')], data$id), 
     function(dat) Filter(nrow, Map(merge, lapply(dat, 
        function(x) stack(table(x))), lapply(low, stack)))))

do.call(rbind, c(Map(cbind, id = names(lst1), lapply(lst1, 
   function(x) do.call(rbind, c(Map(cbind, x, var.name = names(x)),
          make.row.names = FALSE)))), make.row.names = FALSE))
#  id values ind var.name
#1 AA      1   7        Y
#2 AA      3   9        Y
#3 CC      2   3        X

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