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Tip: Reading CSV data with R

To read data with R, use the following procedure:
1. Make sure you are in the correct directory. Use the getwd() function to get the current working directory.

getwd() to get current directory

2. Make sure that the file you wish to load is in the selected directory. Otherwise, use the setwd() function to set the correct directory.

setwd() to set the directory where the data resides

3. Use the list.files() function to list the files in the directory and check that the file is in the correct location.

list.files(".") to list files in the directory, ensuring the file you want to read is there

4. Read the CSV file into a variable (e.g. mydata) using the read.csv() function.

read.csv(<filename>) to read the CSV file

5. To view the data, use the View() function.

View the data using the View() function

Potential Errors

One of the potential errors that you can get is the following:

R
data <- read.csv("adult.test", header=TRUE, sep=",")
R
Error in read.table(file = file, header = header, sep = sep, quote = quote,  : 
  duplicate 'row.names' are not allowed

This error can be solved by the row.names=NULL parameter, as shown in the following code:

R
data <- read.csv("adult.test", header=TRUE, sep=",", row.names=NULL)

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