如何将具有不同长度元素的列表转换为数据框

问题描述：

在这里，当我遇到循环时，我经常遇到这种问题.第一个解决了.

Here I meet so often this kind of problem when I have a loop. The first one is solved.

[1]我有一个这样的列表:

[1] I have a list like this:

myList <- list(a = c(1, 2, 3), b = c(4, 5, 6, 7), c= c(9,10))

现在我要像这样将列表转换为data.frame:

now I want to convert the list to a data.frame like this:

    Value
a   1, 2, 3
b   4, 5, 6, 7
c   9, 10

有人用基本R向我展示通用功能吗?

Does anyone show me a general function by basic R?

[2]出现新问题:

mynewList <- list(a = c(1, 2, 3, "f"), b = c(4, 5, 6), c= c(9,10), d=list(1,2))

我想将mynewlist转换为这样的数据框:

I want to convert the mynewlist to a dataframe like this:

    a   b   c   d 
1   1   4   9  1
2   2   5  10  2
3   3   6  na  na
4   f   na na  na

我以前使用下面的命令，它不带d元素即可工作.但它暂时不起作用.

I use the below command before, it works without the d element. but it didnot work for now.

df<-data.frame(lapply(myList, "length<-" , max(lengths(myList))))

有人用基本R向我展示通用功能吗?

Does anyone show me a general function by basic R?

答

1.我们可以使用 `sapply` 和 `paste` :

df <- data.frame(Value = sapply(myList, paste, collapse = ','))

输出:

    Value
a   1,2,3
b 4,5,6,7
c    9,10

df <- data.frame(lapply(mynewList, function(x) {
  x <- unlist(x)
  length(x) <- max(lengths(mynewList))
  return(x)
}))

输出:

  a  b  c  d
1 1  4  9  1
2 2  5 10  2
3 3  6 NA NA
4 f NA NA NA