Beginning R students often run into a problem where a particular R function appears to be no longer working in R or RStudio. The cause of this problem is usually due to the fact that the student has saved the result of an R function to an object that has the same name as an R function.
The following quote from John Chambers is appropriate here:
Everything that exists is an object. Everything that happens is a function call.
John Chambers, quoted in Advanced R, p. 79.
In the context of this particular topic, if one executes the following statements:
> str(mean)
function (x, ...)
> x <- c(1,2,3,4,5)
> mean <- mean(x)
> str(mean)
num 3
>
the base package mean() function is now hidden by an object called mean in the current environment, as evidenced by the change in output from the str() function. There are two ways to access a function that has been hidden by overriding it.
- Eliminate the local environment's version of the object with
rm(), or - Use the package name to specify the exact function to be called, such as
base::mean()
base::mean(x)
[1] 3
After using the rm() function, one can see that the base::mean() function is accessible again without having to include its package name.
> rm('mean')
> mean
function (x, ...)
UseMethod("mean")
<bytecode: 0x000000000c3a7be0>
<environment: namespace:base>
>
Bottom Line: These types of problems can be very difficult to debug in large R programs, so avoid using an R function name as a an object in your code unless you have a specific reason for overwriting the function.