The numeric0 error in r is not actually an error message but rather it represents a numeric vector of length zero. It takes the form of numeric(0) and it is returned any time you call a numeric vector of length zero regardless of how it is created. However, you cannot check for such a vector directly without getting an error message. This is why such a result is a problem.

## what is numeric() in r?

This function has the form of numeric(x) and it produces a vector of length x each place of with has a numeric value zero. If x equals zero then the vector has zero-length and returns numeric(0). There are other similar functions integer() and character() the behave in the same way but character(0) produces a character value of “” instead of a zero. This is nothing to worry about because it is all part of the r code used in R programming designed to produce vectors that contain no data. The only problem comes into play when you try to check for these zero-length vectors.

## The circumstances of this problem.

The numeric0 error in r occurs when you try to access the zeroth position in a numeric vector. It does not occur when dealing with a missing value or a non numeric argument but when dealing with numeric data. If the factor variable does not contain a number, accessing the zeroth position will create a similar result.

```
> a = c(1,2.5,3.333,4)
> a
[1] 1.000 2.500 3.333 4.000
> a[0]
numeric(0)
```

Note that in this example, we got the problem because we accessed the zeroth position of the vector. It seems to be the only thing that triggers this problem.

```
> b=c()
> b
NULL
> b[0]
NULL
```

Even if you set an empty numeric vector it does not create this problem, all it does is produce a NULL result.

## What is causing this problem?

The cause of this problem to bets be illustrated diagram of a vector in R.

`a = [1] [2] [3] [4]...`

Now you can access any place in “a” with the code a[x]. Note the fact that there is no position zero this means that if you use the code a[0] you are selecting a non-existing position in this object as a result one would expect it to return an error but instead, R is set up such that position zero returns and length of zero. While this avoids an error message it creates a situation where detecting this problem in your equation or character string is tricky.

## How to fix this problem.

At first glance you would think that the solution would be a simple matter of avoiding calling a zeroth position of any object, however, this problem can show up even if you are not directly calling a zeroth position. This is because any number of r functions associated with such a data type can produce a vector of zero length.

You may also think all you need to do is use an if statement in your r code such as the example below.

```
> if(numeric(0)) x=1
Error in if (numeric(0)) x = 1 : argument is of length zero
```

Unfortunately, as you can see here any logical value argument of length zero will produce an error message. As a result, you have not fixed the problem.

`if(length(variable)> 0) {action}`

This is the proper fix for the problem because it allows you to catch a length-zero argument because the length() function returns a zero in such cases.

Because this is not actually an error message as long as you do not have to apply the object to a function you do not have a problem. However, since most functions will not take an argument of length zero it can cause other problems. The simplest of any methods is to check the length and only apply the numeric value variable to a function if it has a length greater than zero. This will help you to avoid and indeed fix the problem in the R programming languages in any future equation or character string.

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