You may sometimes encounter the following message in R:

The following objects are masked from 'package:stats': filter, lag

This message appears when you load some package in R that contains functions that share names with functions that are already loaded from some other package in your current environment.

For example, suppose I load the dplyr package in R:

**library(dplyr)
Attaching package: 'dplyr'
The following objects are masked from 'package:stats':
filter, lag
The following objects are masked from 'package:base':
intersect, setdiff, setequal, union
**

From the output we can observe:

1. The functions called **filter** and **lag** are masked from the R stats package.

- If we use filter() or lag() in our R code, the filter() and lag() functions from
**dplyr**will be used since it was the package loaded most recently that contains these functions.

2. The functions called **intersect**, **setdiff**, **setequal**, and **union **are masked from the R base package.

- If we use intersect(), setdiff(), setequal(), or union() in our R code, these functions from
**dplyr**will be used since it was the package loaded most recently that contains these functions.

**How to Use Masked Functions**

Suppose you would like to use the **intersect()** function from the **base** R package, but it is currently masked since there is an **intersect()** function that exists in the **dplyr** package we loaded more recently.

To explicitly use the **intersect()** function from **base** R, you can use the following syntax with double colons:

**base::intersect(x, y)
**

In practice, you’ll most likely load several packages in your R environment at once.

To ensure that you’re using the function from some desired package, you can always type the package name with double colons in front of the function name.

**Additional Resources**

The following tutorials explain how to perform other common operations in R:

How to Interpret glm Output in R

How to Interpret ANOVA Results in R

How to Handle R Warning: glm.fit: algorithm did not converge