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Get the Minimum Value in an R List

Lists are used in R to store one-dimensional data. Unlike vectors that can only store values of the same type, a list in R can store values of different types together. Although vectors are more commonly used in R, it can be handy to know some common operations on lists. In this tutorial, we will look at how to get the minimum value in an R list with the help of some examples.

How to get the min value in a list in R?

You can use a combination of the unlist() function and the min() function in R to get the minimum value in a list. The following is the syntax –

# get the min value in a list
min(unlist(ls), na.rm=FALSE)

First, use the unlist() function to convert the list into a vector, and then use the min() function to get the minimum value. The following are the arguments that you can give to the min() function in R.

  • x – The vector for which you want to compute the min value.
  • na.rm – (Optional argument) Indicates whether to remove missing values before computing the minimum. It is FALSE by default.

The min() function returns the min value in the passed vector.

Examples

Let’s look at some examples of using the above method to get the min value in a list.

Minimum value in a list of numbers

First, let’s see what happens if we directly apply the min() function to a list without converting it to a vector.

# create a list of numbers
ls <- list(1, 3, 5, 4)
# min value in list
min(ls)

Output:

Error in min(ls): invalid 'type' (list) of argument

You can see that we get an error. This is because we cannot apply the min() function in R directly to a list.

Now let’s use the above syntax, that is, first convert the list to a vector using unlist() and then apply the min() function.

# create a list of numbers
ls <- list(1, 3, 5, 4)
# min value in list
min(unlist(ls))

Output:

1

We get 1 as the minimum value in the above list, which is the correct answer.

What would happen if there are some NA present values in the list?

Let’s find out.

First, we will create a list with some NA values and then apply the same syntax as above without any additional arguments.

# create a list with NA values
ls <- list(1, 3, NA, 5, NA, 4, NA)
# min value in the list
min(unlist(ls))

Output:

<NA>

You can see that we get NA as the output. This is because comparing a value with NA results in an NA in R.

Minimum in a list with NA values

You can pass TRUE to the na.rm parameter of the min() function to exclude missing values when computing the minimum value in a vector. This will ignore the NA values and compute the minimum from the remaining values.

# create a list with NA values
ls <- list(1, 3, NA, 5, NA, 4, NA)
# min value in the list
min(unlist(ls), na.rm=TRUE)

Output:

1

Now we get the minimum value in the above list as 1.

Minimum value in a character list

The above syntax also works similarly for a list of characters. For example, let’s see what we get on applying it to a list of characters.

# create a list of chracters
ls <- list("a", "b", "c", "d")
# min value in the list
min(unlist(ls))

Output:

'a'

Here, we get ‘a’ as the minimum value in the above list which contains the values ‘a’, ‘b’, ‘c’, and ‘d’.

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Author

  • Piyush

    Piyush is a data scientist passionate about using data to understand things better and make informed decisions. In the past, he's worked as a Data Scientist for ZS and holds an engineering degree from IIT Roorkee. His hobbies include watching cricket, reading, and working on side projects.