数据帧输出与R中的预期不同

Question

以下是我写的程序，

func <- function(id = 1:200)
{
dir_char <- as.character(directory) ### changing directory input to character
set_dir <- paste('C:/Users/Junk/Documents/',dir_char,sep="") ### setting working directory path
setwd(set_dir)  ### setting input directory as working directory
count <- 0
for (i in id)   ### going through the id values
{
    id_char <- as.character(i)   ### changing id value to character for setting the file name
    new_file <- data.frame(read.csv(paste(id_char,".csv",sep="")))
    mod_file <- data.frame(new_file[complete.cases(new_file),])
    count <- nrow(mod_file) 
    print(count)
    out_file <- data.frame(id = id, nobs = count)
}
return(out_file)}

此功能的输出如下

[1] 1041
[1] 474
[1] 192 
[1] 148
[1] 96
   id nobs
1  2   96
2  4   96
3  8   96
4 10   96
5 12   96

为什么数据帧out_file在每次循环迭代后都没有存储count值，我期望数据帧将print(count)值存储到out_file中。我哪里出错了，请帮我解决问题。

Answer 1

问题在于

`out_file <- data.frame(id = id, nobs = count)`

每个循环都会创建data.frame。然后返回最后一个。您可以更改逻辑并在data.frame结束后创建loop。

解决问题的一种方法是（我修改了功能的相关部分）：

func <- function(id = 1:200)
{
dir_char <- as.character(directory) ### changing directory input to character
set_dir <- paste('C:/Users/Junk/Documents/',dir_char,sep="") ### setting working directory path
setwd(set_dir)  ### setting input directory as working directory

count <- numeric(length(id))
for (i in id)   ### going through the id values
{
    ### changing id value to character for setting the file name
    id_char <- as.character(i)   
    new_file <- data.frame(read.csv(paste(id_char,".csv",sep="")))
    mod_file <- data.frame(new_file[complete.cases(new_file),])
    count[i] <- nrow(mod_file) 
    print(count)

}
 out_file <- data.frame(id = id, nobs = count)
 return(out_file)
}

Answer 2

你做错了一些事。在他的回答中，我的"search.location": "sidebar" 部分解释了。循环正在产生问题。此外，我假设您需要一个MKR一个nobs。如果是这样，试试这个::

id