One error you may encounter in R is:
Error in read.table(file = file, header = header, sep = sep, quote = quote, : duplicate 'row.names' are not allowed
This error usually occurs when you attempt to read a CSV file into R that contains commas at the end of every row in the file except the header row.
This tutorial shares exactly how to fix this error.
How to Reproduce the Error
Suppose we have the following CSV file called my_data.csv:
Notice that there are commas at the end of every row in the file except the header row.
Now suppose we attempt to import this file into R:
#attempt to import CSV into data frame df <- read.csv('my_data.csv') Error in read.table(file = file, header = header, sep = sep, quote = quote, : duplicate 'row.names' are not allowed
We receive an error because there are commas at the end of every row in the file except the header row, which causes R to think that the first column of values are the row names.
Since two of the rows have the same starting value (4), R thinks that there are duplicate row names.
How to Fix the Error
The way to fix this error is to simply use row.names=NULL when importing the file:
#import CSV file into data frame df <- read.csv('my_data.csv', row.names=NULL) #view data frame df row.names column1 column2 column3 1 4 5 7 NA 2 4 2 1 NA 3 7 9 0 NA
We are able to successfully import the CSV file, but the column names are off.
To fix this, we can modify the column names and then drop the last column:
#modify column names colnames(df) <- colnames(df)[2:ncol(df)] #drop last column df <- df[1:(ncol(df)-1)] #view updated data frame df column1 column2 column3 1 4 5 7 2 4 2 1 3 7 9 0
The data frame is now in the correct format.
Related: How to Use ncol Function in R
The following tutorials explain how to troubleshoot other common errors in R:
How to Fix in R: names do not match previous names
How to Fix in R: longer object length is not a multiple of shorter object length
How to Fix in R: contrasts can be applied only to factors with 2 or more levels