Linear referencing

```
s2_project(x, y, radius = s2_earth_radius_meters())
s2_project_normalized(x, y)
s2_interpolate(x, distance, radius = s2_earth_radius_meters())
s2_interpolate_normalized(x, distance_normalized)
```

- x
A simple polyline geography vector

- y
A simple point geography vector. The point will be snapped to the nearest point on

`x`

for the purposes of interpolation.- radius
Radius of the earth. Defaults to the average radius of the earth in meters as defined by

`s2_earth_radius_meters()`

.- distance
A distance along

`x`

in`radius`

units.- distance_normalized
A

`distance`

normalized to`s2_length()`

of`x`

.

`s2_interpolate()`

returns the point on`x`

,`distance`

meters along the line.`s2_interpolate_normalized()`

returns the point on`x`

interpolated to a fraction along the line.`s2_project()`

returns the`distance`

that`point`

occurs along`x`

.`s2_project_normalized()`

returns the`distance_normalized`

along`x`

where`point`

occurs.

```
s2_project_normalized("LINESTRING (0 0, 0 90)", "POINT (0 22.5)")
#> [1] 0.25
s2_project("LINESTRING (0 0, 0 90)", "POINT (0 22.5)")
#> [1] 2501890
s2_interpolate_normalized("LINESTRING (0 0, 0 90)", 0.25)
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POINT (0 22.5)
s2_interpolate("LINESTRING (0 0, 0 90)", 2501890)
#> <geodesic s2_geography[1] with CRS=OGC:CRS84>
#> [1] POINT (0 22.500002)
```