for（seq_along（data_file）中的i：file（file，“ rt”）中的错误：无效的'description'参数

Question

I begin by reading data into R via an Excel file which contains a list of file location and file names:

data_files <- readxl::read_excel("./Data/source_data.xlsx")

Here is what it looks like:

Next I want to iterate over this list using a for loop/seq_along to access each row variable and use the row variable within the read.csv() and then do things:

for(i in seq_along(data_files)){
  x <- read.csv(data_files[[i]], sep= "\t", skipNul = TRUE)
  # DO THINGS
}

When I run the for loop, I get:

Error in file(file, "rt") : invalid 'description' argument

I know it has to do with the iteration not occurring in a manner that I expect because when I do the following the csv is read into R successfully:

path <- "/Users/gerb/Downloads/"
file <- "Who_Has_Seen_crosstab (2).csv"
path_file <- paste(path, file, sep="")

x <- read.csv(path_file, sep= "\t", skipNul = TRUE)

Answer 1

@Rui Barradas gets my vote but it is worth expanding on his answers. from ?seq_along : "seq_along and seq_len return an integer vector." As mentioned you can see this by adding print into a function.

l = tibble(a = c("a","b","C"))
x = tibble(a = c("a","b","C"),
            b = c("x","y","z"))

for(i in seq_along(l)){
    print(l[i])
}

# A tibble: 3 x 1
   a    
 <chr>
1 a    
2 b    
3 C 


for(i in seq_along(x)){
    print(x[i])
 }

> for(i in seq_along(x)){
      print(x[i])
   }

 #A tibble: 3 x 1
 a    
<chr>
1 a    
2 b    
3 C    
# A tibble: 3 x 1
  b    
 <chr>
1 x    
2 y    
3 z   

You don't want the entire vector. It seems that you want to iterate over each row in a tibble. There are others ways to do this, but something like this would be a better approach:

for(i in 1:nrow(l)){
    print(l[i,])
  }

# A tibble: 1 x 1
 a    
<chr>
1 a    
# A tibble: 1 x 1
  a    
 <chr>
1 b 
 .....   

Last point: it is easier to read a copy and paste of R output than a image. Avoiding screen grabs for future questions would be helpful for others.