CSV DataFrame Writer in R

Code Analysis

The provided R code intends to write a given DataFrame to a CSV file. The structure includes package installation, input validation, directory creation, and the actual file-writing process. However, there are a few issues that need addressing:

1. Incorrect Variable Reference: The validation block references PIDTCList instead of the df parameter.
2. Improvement in Documentation: The code comments should clarify which library require pertains to.

Solution Development

Let's refine the function and ensure it adheres to best practices, fixing the variable reference and improving documentation.

Revised Function

# Import necessary libraries
if (!require("utils")) install.packages("utils", dependencies=TRUE)
library(utils)

# Write DataFrame to CSV File
# This function writes a given DataFrame to a specified CSV file within a designated directory.
# 
# @param df DataFrame to be written to CSV. Must be a valid DataFrame object.
# @param file_name Desired name for the output CSV file (without path).
# 
# @throws Error if `df` is not a DataFrame or if `file_name` is not a character string.
# 
# @return NULL
write_df_to_csv <- function(df, file_name) {
  
  # Input validation
  if (!is.data.frame(df)) {
    stop("Error: Input 'df' must be a DataFrame.")
  }
  if (!is.character(file_name) || length(file_name) != 1) {
    stop("Error: 'file_name' must be a single character string.")
  }

  # Create directory if it does not exist
  dir_path <- "Files/CSV"
  if (!dir.exists(dir_path)) {
    dir.create(dir_path, recursive = TRUE)
  }
  
  # Construct the full file path
  file_path <- file.path(dir_path, file_name)

  # Write the DataFrame to CSV
  write.csv(df, file=file_path, row.names=FALSE)
  
  # Inform the user of the completed action
  message(sprintf("DataFrame has been successfully written to '%s'", file_path))
}

# Example Usage
# Assuming `example_df` is a DataFrame object available in the environment
# example_df <- data.frame(A=1:5, B=6:10)  # Sample Data Frame, not needed if `example_df` is pre-existing
write_df_to_csv(example_df, "example_output.csv")

Explanation

1. Code Imports and Library Initialization:

   • Ensures utils library is loaded.

2. Function write_df_to_csv:

   • Validates the df input to ensure it is a DataFrame.
   • Validates file_name to ensure it is a single character string.
   • Checks if the directory exists; if not, creates it.
   • Constructs the full file path using file.path.
   • Writes the DataFrame to the specified CSV file and informs the user upon successful completion.

3. Usage Example:

   • Demonstrates how to use the write_df_to_csv function with a sample DataFrame example_df.

This revised function addresses the initial problems and improves code clarity and correctness.