How to solve R Error in xj[i] : invalid subscript type ‘list’

This error occurs when you try to use a list to subset a data frame. You can solve this error by using the c function to subset the data frame based on a vector. For example,

df_subset <- df[c("x", "z")]

df_subset

This tutorial will go through the error in detail and how to solve it with code examples.

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Example

Let’s look at an example to reproduce the error.

# Create a data frame with three columns

df <- data.frame(x = rnorm(10), 
                 y = letters[1:10],
                 z = 1:10)
df

             x y  z
1  -0.38117846 a  1
2   0.90089817 b  2
3  -0.06359607 c  3
4   0.07582160 d  4
5   0.98323210 e  5
6   1.91295945 f  6
7  -1.56388794 g  7
8   0.93328058 h  8
9  -0.75076193 i  9
10  1.44142624 j 10

Next, we will try to subset the data frame using a list with two column names.

# Attempt to subset data frame using list

df_subset <- df[list("x", "z")]

Let’s run the code to see what happens:

Error in `[.default`(df, list("x", "z")) : invalid subscript type 'list'

The error occurs because we cannot subset a data frame with a list in R.

Solution

We can solve the error by switching out the list function with the c function. We need to use a vector to subset the data frame instead of a list. Let’s look at the revised code:

df_subset <- df[c("x", "z")]

df_subset

Let’s run the code to get the result:

            x  z
1  -0.38117846  1
2   0.90089817  2
3  -0.06359607  3
4   0.07582160  4
5   0.98323210  5
6   1.91295945  6
7  -1.56388794  7
8   0.93328058  8
9  -0.75076193  9
10  1.44142624 10

We successfully created a new data frame which is a subset of the original data frame.

Summary

Congratulations on reading to the end of this tutorial!

For further reading on R-related errors, go to the articles: 

• How to Solve R Error in sort.int(x, na.last = na.last, decreasing = decreasing, …) : ‘x’ must be atomic
• How to Solve R Error as.Date.numeric(x) : ‘origin’ must be supplied
• How to Solve R Error: invalid (do_set) left-hand side to assignment

Go to the online courses page on R to learn more about coding in R for data science and machine learning.

Have fun and happy researching!