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Comparison operators for linear time (mt_linear)

Source: R/compare.R
mt_linear-compare.Rd

Discrete linear time values represent a closed interval spanning their chronon (e.g. year(2020) spans every instant from the start of 2020 to the end of 2020), while continuous linear time values represent a single instant. Comparing two mt_linear vectors therefore compares the start/end instants of the (possibly zero-width) interval each value represents:

  • a == b iff start(a) == start(b) and end(a) == end(b)

  • a < b iff end(a) <= start(b) (i.e. before with or without a gap)

  • a > b iff start(a) >= end(b) (i.e. after with or without a gap)

  • a <= b iff end(a) <= end(b) (right-bound comparison)

  • a >= b iff start(a) >= start(b) (left-bound comparison)

This is not a total order for comparisons between time points at different granularities: <=/>= are not shorthand for (< or ==)/(> or ==). For example, yearquarter("2020 Q3") <= year("2020") is TRUE despite yearquarter("2020 Q3") < year("2020") and yearquarter("2020 Q3") == year("2020") being FALSE.

The inequality operators </> and <=/>= are useful conjugations of Allen's interval algebra for common data manipulation needs. The complete set of Allen's 13 base relations are documented in allen-interval-algebra.

Usage

# S4 method for class 'mt_linear'
e1 == e2
# S4 method for class 'mt_linear'
e1 != e2
# S4 method for class 'mt_linear'
e1 < e2
# S4 method for class 'mt_linear'
e1 <= e2
# S4 method for class 'mt_linear'
e1 > e2
# S4 method for class 'mt_linear'
e1 >= e2

Arguments

e1, e2

mt_linear vectors (or values castable to one, such as plain numeric vectors in the other operand's chronon, read from its epoch as mixtime() reads them, so year(x) == 2026L compares with 2026).

Value

A logical vector.