Read multiple csv within a function without a for loop

[rjo]

I am trying to read multiple .csv files but within a function with a single input variable, so I can modify each file with the same of lines of code. All my files (All_0320, Part_0320, etc.) are located in the same folder.

func1 <- function(file){
   setwd("C:/Users/Myname/FolderWithData/")
   z1 <- read.csv(paste0(file,".csv",sep=""))
#lines of code that modify z1 
 return(z1)
}

num1 <- func1(All_0320)
num2 <- func1(Part_0320)

This gives me an error " Error in file(file, "rt") : invalid 'description' argument "

What am I doing wrong?
I used the code from here as an example: Doing Macros in R

[ZykeZero]

Your error is that you are entering func1(All_0320) instead of func1("All_0320").

library(tidyverse)

load_csv_file <- function(file_name) {
  
  address <- "C:/Users/Myname/FolderWithData/"
  
  read_csv(paste0(address, file_name)) %>%
    mutate(new_col = sum(old_col))
}

my_data <- load_csv_file("banana prices.csv")

[rjo]

Thank you so much, that was it! I was trying to use the names of the files "All_0320" for a column in the output result but might not be able to do that with the quotes around them.. but that's ok.

[ZykeZero]

I've commented out the CSV portion so that you can run this on your machine and see how it works for yourself. Just replace df %>% with the commented out line and you're good to go.

df <- data.table(a = 1:10)

load_csv_file <- function(file_name, col_name) {
  
  address <- "C:/Users/Myname/FolderWithData/"
  
  # read_csv(paste0(address, file_name)) %>%
  
  df %>% 
    mutate("{col_name}" := sum(a))
}

load_csv_file("banana prices.csv", "new_column_name")

[rjo]

@ZykeZero

 df %>% 
    # mutate(col_name = sum(a))
    mutate("{col_name}" := sum(a))

Thanks again @ZykeZero. But the df %>%
# mutate(col_name = sum(a))
mutate("{col_name}" := sum(a)) part is not doing anything on my end...

mine looks like this:

df %>% 
mutate ("{col_name}" := value )

value is the name of the original column.

[rjo]

Nevermind, I had a small typo and now it's fixed and working. Appreciate your help so much!

[ZykeZero]

"{col_name}" is the location in the function that R will replace with what you pass to col_name in the function.

function(file_name, col_name)

you have to look at the whole piece that I had provided. I created a dataframe with the column a and values 1:10
df <- data.table(a = 1:10)

and then created the function.

And then used the function so that you could see in the output that "new_column_name" was the name of the new column created.