Performance
A benchmark can reveal how many route gradients can be calculated per second:
e = dem_lisbon_raster
r = lisbon_road_network
et = terra::rast(e)
res = bench::mark(check = FALSE,
slope_raster = slope_raster(r, e),
slope_terra = slope_raster(r, et)
)
res
#> # A tibble: 2 × 6
#> expression min median `itr/sec` mem_alloc `gc/sec`
#> <bch:expr> <bch:tm> <bch:tm> <dbl> <bch:byt> <dbl>
#> 1 slope_raster 45.7ms 46.9ms 21.0 16.12MB 9.00
#> 2 slope_terra 43.2ms 44.3ms 19.6 1.96MB 4.90
That is approximately
routes per second using the raster
and
terra
(the default if installed, using
RasterLayer
and native SpatRaster
objects)
packages to extract elevation estimates from the raster datasets,
respectively.
The message: use the terra
package to read-in DEM data
for slope extraction if speed is important.
To go faster, you can chose the simple
method to gain
some speed at the expense of accuracy:
e = dem_lisbon_raster
r = lisbon_road_network
res = bench::mark(check = FALSE,
bilinear1 = slope_raster(r, e),
bilinear2 = slope_raster(r, et),
simple1 = slope_raster(r, e, method = "simple"),
simple2 = slope_raster(r, et, method = "simple")
)
res
#> # A tibble: 4 × 6
#> expression min median `itr/sec` mem_alloc `gc/sec`
#> <bch:expr> <bch:tm> <bch:tm> <dbl> <bch:byt> <dbl>
#> 1 bilinear1 45.3ms 45.6ms 21.7 5.28MB 21.7
#> 2 bilinear2 43.4ms 44.7ms 22.4 1.86MB 4.97
#> 3 simple1 36.2ms 37.1ms 26.3 1.97MB 7.90
#> 4 simple2 37.5ms 37.9ms 25.8 1.98MB 7.73