getCurve

Determine whether the river is bend within a specific area and calculate a numeric value for the strength and direction of this bend, i. e. how small the curve radius is and whether it is a turn right (value > 1) or a turn left (value < 1). This is achieved by placing a buffer of 50 m sf.afe_sides_buffered_axis around sf.axis and afterwards comparing the overall area of this buffer on the left and right hand side of the river axis within the specified area.

Usage

getCurve(x, b, bu = b)

Arguments

x

must be a single integer indexing one hectometer polygon of sf.afe_csa along the River Elbe. x must be element of seq(from = 1, to = length(sf.afe_csa), by = 1).

b

must be a single numeric specifying a buffersize to be included for the axis length computations around the indexed hectometer in m.

bu

is an optional single numeric specifying a separate upstream buffersize to be included for the axis length computations around the indexed hectometer in m (default = b).

Value

list with items value (numeric)and txt (character) indicating the direction c("left", "right").

See also

sf.afe_csa, sf.axis, sf.afe_sides_buffered_axis

Examples

   getCurve(3900, 200)
#> Warning: attribute variables are assumed to be spatially constant throughout all geometries
#> $value
#> [1] 1.002558
#> 
#> $txt
#> [1] "left"
#> 
   getCurve(3963, 200)
#> Warning: attribute variables are assumed to be spatially constant throughout all geometries
#> $value
#> [1] 0.9863707
#> 
#> $txt
#> [1] "right"
#>