How to Handle “undefined columns selected” in R?

In this article, we will discuss how to handle “undefined columns selected” error in R Programming Language.

This error is specific to dataframe in R. This type of error will occur when we select a subset of a data frame and forget to add a comma.

Example: Check the error in the dataframe

Here we created a dataframe with 3 columns and select the values in which the second column value is greater than 45

# create dataframe with 4 rows and 3 columns 

data = data.frame(marks1=c(98, 90, 89, 78),  

                  marks2=c(100, 89, 91, 76),  

                  marks3=c(78, 89, 79, 94)) 

# display 

print(data) 

# now select values from marks2 column  
# which are greater than 45 
data[data$marks1 > 45]

Output:

This is because of neglecting comma(,) behind the value. The dataframe must choose the column after comma operator. So we have to keep comma.

Example:

# create dataframe with 4 rows and  
# 3 columns 

data = data.frame(marks1=c(98, 90, 89, 78), 

                  marks2=c(100, 89, 91, 76), 

                  marks3=c(78, 89, 79, 94)) 

# display 

print(data) 

# now select values from marks2 column  
# which are greater than 90 
data[data$marks1 > 90, ]