The “error: attempt to use zero-length variable name” error message often occurs when you try to run rmarkdown code as regular r code. This is particularly the case when it includes the backtick character. The best solution is to omit that section of code from what you are running. While this does not technically fix the problem, it does prevent it.
Description of the problem
The “error: attempt to use zero-length variable name” error message occurs when you are using the global environment as a rmd editor, and you try to run code that has backtick characters. These are disallowed characters, and their presence causes a problem. This is not a problem with the read csv function, parser function, and surprisingly not even variable names not even non-syntactic variable names. A rmarkdown chunk has plain text and a character can cause problems if it is disallowed. This is a problem that comes from mixing two different types of code in the same window. When you do this, you will inevitably run into problems. Naturally, you can get away with it as long as you do not run the markdown code, but the risk will always be there.
Explanation of the Problem
Here are some r code illustrating how to cause the “error: attempt to use zero-length variable name” error message. It is a simple bit of code that would run normally except for the first part.
> “`{r cars}
Error: attempt to use zero-length variable name
> data(cars)
> summary(cars)
speed dist
Min. : 4.0 Min. : 2.00
1st Qu.:12.0 1st Qu.: 26.00
Median :15.0 Median : 36.00
Mean :15.4 Mean : 42.98
3rd Qu.:19.0 3rd Qu.: 56.00
Max. :25.0 Max. :120.00
The problem occurs following the line that has the backtick characters. If you are trying to run this code, it is fortunate that r studio goes on to run the rest of the code, such that you still get the results you are looking for.
How to fix the Problem
Here are two examples of how to fix or at least avoid the “error: attempt to use zero-length variable name” error message. It basically fixes the problem by eliminating and not actually fixing the problem.
> data(cars)
> summary(cars)
speed dist
Min. : 4.0 Min. : 2.00
1st Qu.:12.0 1st Qu.: 26.00
Median :15.0 Median : 36.00
Mean :15.4 Mean : 42.98
3rd Qu.:19.0 3rd Qu.: 56.00
Max. :25.0 Max. :120.00
This bit of r code solves this problem by simply not running the line containing the backtick characters. This is a case of fixing the problem by eliminating it. By not running the line that causes the problem you are avoiding it and still getting the results that you are looking for.
> {cars}
speed dist
1 4 2
2 4 10
3 7 4
4 7 22
5 8 16
6 9 10
7 10 18
8 10 26
9 10 34
10 11 17
11 11 28
12 12 14
13 12 20
14 12 24
15 12 28
16 13 26
17 13 34
18 13 34
19 13 46
20 14 26
21 14 36
22 14 60
23 14 80
24 15 20
25 15 26
26 15 54
27 16 32
28 16 40
29 17 32
30 17 40
31 17 50
32 18 42
33 18 56
34 18 76
35 18 84
36 19 36
37 19 46
38 19 68
39 20 32
40 20 48
41 20 52
42 20 56
43 20 64
44 22 66
45 23 54
46 24 70
47 24 92
48 24 93
49 24 120
50 25 85
> data(cars)
> summary(cars)
speed dist
Min. : 4.0 Min. : 2.00
1st Qu.:12.0 1st Qu.: 26.00
Median :15.0 Median : 36.00
Mean :15.4 Mean : 42.98
3rd Qu.:19.0 3rd Qu.: 56.00
Max. :25.0 Max. :120.00
This example changes the line with the backtick characters into legitimate r code. It does, however, produce a very long result.
The “error: attempt to use zero-length variable name” error message is a strange one to deal with. It is one you are not likely to run across frequently. It is, however, an easy one to deal with.