ROBUSTNESS: x & y should be x && y

[HenrikBengtsson]

Hi, while troubleshooting some future devel issues regarding lidR, I spotted:

https://github.com/Jean-Romain/lidR/blob/82ef90be73cd3e8e86a49e8cb0d920e1fa751927/R/clusters_apply.R#L129
https://github.com/Jean-Romain/lidR/blob/82ef90be73cd3e8e86a49e8cb0d920e1fa751927/R/clusters_apply.R#L147

I think you meant to use && (scalar) instead of & (vector).

[Jean-Romain]

I can do it. I do agree that programmatically speaking it is more correct that way but I can't see how it might be a problem. & and && are similar enough with length 1 vector for the two expressions with & or && to behave almost the same.

Actually in R I always use & unless I explicitly want the second term not being evaluated if the first is FALSE like in !is.null(x) && x == 0

[HenrikBengtsson]

I do agree that programmatically speaking it is more correct that way but I can't see how it might be a problem. & and && are similar enough with length 1 vector for the two expressions with & or && to behave almost the same.

Sorry, I should have been more clear. Technically, yes, both work, if and only if, LHS and RHS are of length one. However, if one make a mistake somewhere causing one of them to have length > 1, using && will eventually catch the mistake instead of propagating an unknown behavior. That's why I proposed it. See below for an example. When I run revdep checks on future, matrixStats, etc. with these checks enabled, I keep spotting quite a few number of packages with such bugs.

Current behavior in R:

$ R --quiet --vanilla 
> c(TRUE, FALSE) && TRUE
[1] TRUE
> 

Future/eventual behavior in R:

$ _R_CHECK_LENGTH_1_LOGIC2_=true R --quiet --vanilla
> c(TRUE, FALSE) && TRUE
Error in c(TRUE, FALSE) && TRUE : 
  'length(x) = 2 > 1' in coercion to 'logical(1)'

[HenrikBengtsson]

To clarify further; I did not spot this mistake in lidR; I just happened to see the code while troubleshooting #435

[Jean-Romain]

Understood. Thanks. I'm trying to use && more consistently but & working every-time old habits are hard to shake off.