将列表转换为R中具有特定列名称的数据框 [英] converting list to data frame with specific column names in R

问题描述

我已经查看了此处的其他类似主题，但尚未找到我的问题的答案.我在for循环中构建了一个列表，希望将其转换为数据框.最终列表如下所示:

I've reviewed the other similar threads on here but haven't found the answer to my question yet. I'm building a list in a for loop that I want to convert to a data frame. The final list looks like this:

[[1]]
[1] 117

[[2]]
[1] 1041

[[3]]
[1] 243

[[4]]
[1] 474

[[5]]
[1] 402

我想将其转换为具有特定列名称的数据框:ID和Nob.因此，例如，对于数据帧中的第5行，ID的行值将为5，而鲍勃的值将为402.运行此代码:

I want to convert this to a data frame, with specific column names: ID and nobs. So for example for 5th row in the data frame, the row value for ID would be 5 and the value for bobs would be 402. Running this code:

d <- data.frame(cbind(l))

给我列，但没有名称.如何以及在哪里可以指定列名?我只是在学习R.谢谢您的帮助.

gives me the columns but without the names. How and where can I specify the column names? I am just learning R. Thanks for any help.

这是我的功能的完整代码:

this is the full code for my function:

complete <- function(directory, id) {
        files_full <- list.files(directory, full.names = TRUE)
        l <- list()
        for (i in id){
                nobs <- sum(complete.cases(read.csv(files_full[i])))
                l[i] <- nobs
        }
        d <- data.frame(cbind(l))
        d
}

推荐答案

您可以尝试以下操作:

l <- list(a=305,b=354,c=436,d=36)
> l
$a
[1] 305
$b
[1] 354
$c
[1] 436
$d
[1] 36

data.frame(id=names(l), nobs=unlist(l))
  id nobs
a  a  305
b  b  354
c  c  436
d  d   36
data.frame(l)
    a   b   c  d
1 305 354 436 36
unlist(l)
a   b   c   d 
305 354 436  36

请注意，第一个和第二个是data.frame的，而最后一个是数字矢量.

Note that first and second are data.frame's, but last is named numeric vector.

列表中可能没有您的姓名，例如您的示例. 我假设您要创建命名列表并将其转换为data.frame ... 如果要在列表中设置名称，则应该可以:

Probably you don't have any names in your list as in your example. I presume that you want to create named list and convert it to data.frame... If you want to set names to your list it should work:

complete <- function(directory, id) {
    files_full <- list.files(directory, full.names = TRUE)
    l <- vector(mode='list', length=length(files_full))
    for (i in files_full){
            nobs <- sum(complete.cases(read.csv(i)))
            l[i] <- nobs
    }
    d <- data.frame(cbind(l))
    d
}

但是让我们尝试一下: sapply(list.files(), function(x)sum(complete.cases(read.csv(x)))) 它应该返回如下内容:

But let's try this: sapply(list.files(), function(x)sum(complete.cases(read.csv(x)))) It should return something like:

a.csv   b.csv    c.csv
 2153     326      235

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