What does "Error: object '<myvariable>' not found" mean?

Question

I got the error message:

Error: object 'x' not found

Or a more complex version like

Error in mean(x) : error in evaluating the argument 'x' in selecting a method for function 'mean': Error: object 'x' not found

What does this mean?

Answer 1

The error means that R could not find the variable mentioned in the error message.

The easiest way to reproduce the error is to type the name of a variable that doesn't exist. (If you've defined x already, use a different variable name.)

x ## Error: object 'x' not found 

The more complex version of the error has the same cause: calling a function when x does not exist.

mean(x) ## Error in mean(x) :  ##   error in evaluating the argument 'x' in selecting a method for function 'mean': Error: object 'x' not found 

Once the variable has been defined, the error will not occur.

x <- 1:5 x ## [1] 1 2 3 4 5      mean(x) ## [1] 3 

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You can check to see if a variable exists using ls or exists.

ls()        # lists all the variables that have been defined exists("x") # returns TRUE or FALSE, depending upon whether x has been defined. 

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Errors like this can occur when you are using non-standard evaluation. For example, when using subset, the error will occur if a column name is not present in the data frame to subset.

d <- data.frame(a = rnorm(5)) subset(d, b > 0) ## Error in eval(expr, envir, enclos) : object 'b' not found 

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The error can also occur if you use custom evaluation.

get("var", "package:stats") #returns the var function get("var", "package:utils") ## Error in get("var", "package:utils") : object 'var' not found 

In the second case, the var function cannot be found when R looks in the utils package's environment because utils is further down the search list than stats.

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In more advanced use cases, you may wish to read:

• The Scope section of the CRAN manual Intro to R and demo(scoping)
• The Non-standard evaluation chapter of Advanced R

Answer 2

While executing multiple lines of code in R, you need to first select all the lines of code and then click on "Run". This error usually comes up when we don't select our statements and click on "Run".