Appendix B — Common R errors and how to fix them

In these error messages, the code blah represents the function, object or value that the error relates to.

Common R errors

Error message	How to fix it
there is no package called 'blah'	You have either mis-typed the package name or the package is not installed. Check the spelling or use install.packages() to install the package.
`could not find function	You have either mis-typed the function name or the package containing that function is not loaded. Check the spelling or use library() to load the package.
object 'blah' not found	You have either mis-typed the name of the object or the object does not exist. Check the spelling and make sure you have run the code that creates the object. This error can also occur when you have forgotten to put quotes around a character value in an argument, since R treats words without quotes around them as the names of objects. In this case, check that you have used quote marks around any character values in your code.
'blah' does not exist in current working directory	You have either mis-typed the name of a file that R is trying to access or the file does not exist in the location you have specified. Check the spelling and make sure the file exists.
non-numeric argument to binary operator	You have tried to use a mathematical operator such as + or - with a non-numeric value. For example, you might have written the code 1 + blah thinking that blah holds a numeric value, but if blah actually holds a character value then trying to add it to 1 makes no sense. Check that any objects in your code have the values you expect them to.
object of type 'closure' is not subsettable	You have tried to use a function as if it is an object, which can happen when you store data in an object that has the same name as an R function (most commonly, when you store some data in an object called data, since there is a function called data()). The circumstances that produce this error are often not simple to understand, so the best way to handle this error is to avoid it by not naming objects using the names of functions.
no applicable method for 'blah' applied `to an object of class	Some R functions (called generic functions) work in different ways depending on what type of object you use them on. But if you use a generic function on an object that it does not know how to handle, you will see this error. Check the object(s) that you provided to the function causing the error to make sure it is the type of object you are expecting it to be.
`unexpected numeric constant in	You have a typo somewhere in your code. Check the line of code producing the error to make sure it is formatted correctly. The most common typos that cause this error are a missing comma or closing parenthesis, but there are several other typos that can cause similar errors.
`unused argument (var =	You have used an argument name in a function that does not understand it. Check the manual page for that function.
`argument	You have used a function without providing all the necessary arguments. Check the manual page for that function.
The pipe operator requires a function call as RHS	There is a pipe operator at the end of the final line of a code pipeline (or what R thinks should be the final line), or you have omitted the parentheses at the end of a function name.