将嵌套列表(不等长)转换为数据帧

Question

我有一个嵌套列表; 对于某些指数,缺少一些变量.

[[1]]
    sk   ques   pval 
  "10" "sfsf" "0.05" 

[[2]]
    sk   ques   pval   diff 
 "24" "wwww" "0.11"  "0.3" 

[[3]]
    sk   ques   pval   diff    imp 
  "24" "wwww" "0.11"  "0.3"    "2" 

如何将其转换为数据框,对于第一行,数据$ diff [1] = NA？以上情况将是具有5个变量和3个观察的数据帧.

数据框中的变量数将是列表元素中唯一名称的数量,列表中的缺失值将替换为NA.

谢谢,

编辑:数据格式

list(structure(c("10", "sfsf", "0.05"), .Names = c("sk", "ques", 
"pval")), structure(c("24", "wwww", "0.11", "0.3"), .Names = c("sk", 
"ques", "pval", "diff")), structure(c("24", "wwww", "0.11", "0.3", 
"2"), .Names = c("sk", "ques", "pval", "diff", "imp")))

Answer 1

我们得到length的list与循环元素("INDX") sapply.在最近的版本中R,我们可以使用lengths替换sapply(.., length)步骤.我们将length每个元素的 max长度从'indx'(length<-)更改为长度,从而填充长度小于长度NA的list元素末尾的填充值max.我们可以rbind将list元素转换为data.frame并更改列名.

 indx <- sapply(lst, length)
 #indx <- lengths(lst) 
 res <- as.data.frame(do.call(rbind,lapply(lst, `length<-`,
                          max(indx))))

 colnames(res) <- names(lst[[which.max(indx)]])
 res
 # sk ques pval diff  imp
 #1 10 sfsf 0.05 <NA> <NA>
 #2 24 wwww 0.11  0.3 <NA>
 #3 24 wwww 0.11  0.3    2

数据

 lst <- list(structure(c("10", "sfsf", "0.05"), .Names = c("sk", "ques", 
 "pval")), structure(c("24", "wwww", "0.11", "0.3"), .Names = c("sk", 
 "ques", "pval", "diff")), structure(c("24", "wwww", "0.11", "0.3", 
 "2"), .Names = c("sk", "ques", "pval", "diff", "imp")))