23 May 2024

Posted on:

15 May 2024

0

# Resolved:Solution of the excercice is printing an ERROR

Hello this part of the code in the solution return an error : ((-2:2) >= 0) && ((-2:2) <= 0)
"'length = 5' in coercion to 'logical(1)'"

Instructor
Posted on:

23 May 2024

0

Hi Houda,

thanks for reaching out!

The error you're encountering is due to attempting to use a logical operation on a vector that results in a logical vector longer than one element in a context where a single logical value is expected. Specifically, in R, the expression `(-2:2) >= 0` results in a logical vector of length 5 (since `-2:2` generates the sequence `-2, -1, 0, 1, 2`), and similarly for `(-2:2) <= 0`.

Here's a breakdown of the issue:

1. `(-2:2)` generates the sequence: `-2, -1, 0, 1, 2`.
2. `(-2:2) >= 0` generates the logical vector: `FALSE, FALSE, TRUE, TRUE, TRUE`.
3. `(-2:2) <= 0` generates the logical vector: `TRUE, TRUE, TRUE, FALSE, FALSE`.

Combining these with the `&&` operator is where the problem occurs. The `&&` operator in R is designed for scalar logical operations, not for vectorized ones. When you use `&&` with vectors, R expects both sides of the `&&` to be single logical values, but in your case, they are vectors of length 5. This mismatch causes the error.

To perform element-wise logical operations on vectors, you should use the `&` operator instead of `&&`. Here's the corrected expression:

``((-2:2) >= 0) & ((-2:2) <= 0)``

This will correctly generate the logical vector you are looking for:

``FALSE, FALSE, TRUE, FALSE, FALSE``

This represents the positions in the vector `-2, -1, 0, 1, 2` that are both greater than or equal to 0 and less than or equal to 0, which is only `0` itself.

If you need to use this logical vector in a context where a single logical value is expected, you might need to further process it (e.g., using `any`, `all`, or other similar functions depending on your requirements). For example, if you want to check if any of the conditions are `TRUE`, you can use:

``any(((-2:2) >= 0) & ((-2:2) <= 0))``

This will return a single logical value `TRUE` if any element in the combined logical vector is `TRUE`, otherwise it will return `FALSE`.

Hope this helps!

Best,

365 Eli