number-pairs

Javascript utility for dealing with ranges of numbers and/or dates expressed as length-2 arrays.

contains

tests if a range expressed as a pair of numbers contains some other value

contains([2,6],4) // true, 4 is in contained in the range 2-6
contains([2,6],7) // false

A range is considered to contain its lower bound but not its upper:

contains([2,6],2)       // true
contains([2,6],5.99)    // true
contains([2,6],6)       // false

centredOn

Creates a new range of the same size, but centred around a new value (think panning):

centredOn([2,3], 10) // [-9.5, 10.5]

mid

Calculates the midpoint of a pair of numbers

mid(-5, 5) // 0
mid(5, 10) // 7.5
 

pairExtent

pairExtent(-1, 10) // 11
 

interpolateBetweenPair

interpolateBetweenPair([5,10], 0.5) // 7.5
interpolateBetweenPair([5,10], 0)   // 5
interpolateBetweenPair([5,10], 1)   // 10

rangesOverlap

rangesOverlap([1,4],[3,8]) // returns true - these ranges overlap
rangesOverlap([1,4],[5,8]) // returns false - these ranges do notoverlap

overlap

overlap(a,b,c,d)
// same as:
rangesOverlap([a,b], [c,d])
 

expandPair

Expand a range so that it the returned value is proptionally larger (or smaller) than the given value.

it holds that:

extent( expand( r, n ) ) / extent(r) === n

so, to double the extent of a range:

expand( r, 2 )

to half the extent of a range:

expand( r, 0.5 )

max

Enforces the maximum extent of a range, while keeping the centre point the same (think viewport minimum)

max([a,b], maxExtent)

min

Enforces the minimum extent of a range, while keeping the centre point the same (think viewport minimum)

min([a,b], minExtent)