noswimming

The goal of noswimming is to prevent animals from leaving the ocean. (i.e. swimming on land is not allowed)

WIP

The name isn’t very serious, or accurate, or what we want. TBD

Installation

You can install the development version of noswimming like so:

## install.packages("remotes")
remotes::install_github("mdsumner/noswimming")

Example

This is a basic example which finds the least cost path around land (we get a topographic dataset under the hood to figure this out).

library(noswimming)
#pt <- cbind(c(-90, 90), c(-70, -60))
pt <- cbind(c(138, 153),  c(-36, -23))
path <- lcp(pt)

library(terra)
#> terra 1.7.81

## we get the data in the projection use
plot(path)

## so reproject for longlat use
plot(terra::project(path, "EPSG:4326"), lty = 2, col = "firebrick")
maps::map(add = TRUE)

To turn path into longlat, do this:

ll <- terra::geom(terra::project(path, "EPSG:4326"))[,c("x", "y")]
str(ll)
#>  num [1:55, 1:2] 138 138 139 139 140 ...
#>  - attr(*, "dimnames")=List of 2
#>   ..$ : NULL
#>   ..$ : chr [1:2] "x" "y"

We can also obtain the intermediate datasets used in the above process.

pt1 <- cbind(c(-90, 90), c(-70, -60))
topo <- make_global_topo(pt1)

## here we might customize the min and max value of the topography (from [-Inf,0])
surf <- make_na_surface(topo)

path <- lcp(pt1, surf = surf)
plot(topo)
plot(path, add = TRUE, col = "hotpink")

It’s not really going to be valid in this crs for such long pathways, but we might improve that (you would need a custom projection like Oblique Mercator).

pt2 <- cbind(c(-76, -118), c(-52, 70))
topo <- make_global_topo(pt2)

## here we might customize the min and max value of the topography (from [-Inf,0])
surf <- make_na_surface(topo)

path <- lcp(pt2, surf = surf)
topo[topo > 0] <- NA

plot(topo)
plot(path, add = TRUE, col = "hotpink", lwd = 2)

Code of Conduct

Please note that the noswimming project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.