empty | R Documentation |

A valid interval matrix may contain empty intervals: those with common
endpoints, at least one of which is open. The `empty`

method
identifies these rows.

```
## S4 method for signature 'Intervals'
empty(x)
## S4 method for signature 'Intervals_full'
empty(x)
```

`x` |
An |

Intervals are deemed to be empty when their endpoints are equal and
not both closed, or for `type == "Z"`

, when their endpoints differ
by 1 and both are open. The matrices `x`

and `x[!empty(x),]`

represent the same subset of the integers or the real line.

A boolean vector with length equal to `nrow(x)`

.

Exact equality (`==`

) comparisons are used by `empty`

. See
the package vignette for a discussion of equality and floating point
numbers.

Note that intervals of size 0 may not be empty over the reals, and
intervals whose second endpoint is strictly greater than the first
*may* be empty over the integers, if both endpoints are open.

See `size`

to compute the size of each interval in an
object.

```
z1 <- Intervals( cbind( 1, 1:3 ), type = "Z" )
z2 <- z1; closed(z2)[1] <- FALSE
z3 <- z1; closed(z3) <- FALSE
empty(z1)
empty(z2)
empty(z3)
r1 <- z1; type(r1) <- "R"
r2 <- z2; type(r2) <- "R"
r3 <- z3; type(r3) <- "R"
empty(r1)
empty(r2)
empty(r3)
s1 <- Intervals_full( matrix( 1, 3, 2 ), type = "Z" )
closed(s1)[2,2] <- FALSE
closed(s1)[3,] <- FALSE
empty(s1)
```

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