Append row to CSV using R

In this article, we will see how to append rows to a CSV file using R Programming Language. 

By default, the write.csv() function overwrites entire file content. In order to append the data to a CSV File, use the write.table() method instead and set the parameter, append = TRUE. The write.table method prints its required argument x, upon conversion of the .csv file into the data frame to a file or connection. 

Syntax:

write.table(x, file = "", append = FALSE, quote = TRUE, sep = " ", row.names = TRUE, col.names = TRUE)

Parameters:

• x : The row data in the data frame object
• file : The file to append row to
• sep : The field separator string, that is within each row of x values are separated by this separator.

In case the file is empty, the contents are written on to the .csv file upon creation within the same directory. The following code illustrates the applicability of write.table() method on an empty .csv file. 

Example

# defining the data for the csv file 
# data is organised into 4 columns
data = data.frame(ID = 1:4, Name = c("A","B","C","D"),
                  Post=c("Peon","SDE","Manager","SDE"), 
                  Age = c(23,39,28,39))

# write data to a sample.csv file
write.table(data, file = "sample.csv") 

Output

The following snippet shows how to append a row to the CSV file already composed of a few rows. The changes are made to the specified CSV file, and upon each operation, one-row count is incremented. 

Example:

# defining a row 
row <- data.frame('1', 'A', 'Manager', '24')

# sample csv name
csv_fname = "sample.csv"

# writing row in the csv file
write.table(row, file = csv_fname, sep = ",",
            append = TRUE, quote = FALSE,
            col.names = FALSE, row.names = FALSE)

Output