CMIE CapEx utilities

Data munging

Apply these functions to columns from the CapEx database.

Karmana.latlong_string_to_points — Function

latlong_string_to_points(latlong_string)

Parses a string of the form lat1,long1 : lat2,long2 : lat3,long3 : ... and returns a Vector of Point2e which define points as (long, lat).

Is robust to cutoff errors and other potential issues.

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Karmana.points_weights — Function

points_weights(latlong_strings::Vector{:< AbstractString}, costs::Vector{<: Real})

Parses strings of the form lat1,long1 : lat2,long2 : lat3,long3 : ... and returns a Vector of Point2e which define points as (long, lat), as well as a vector of weights per point. If the string has more than one point defined, the weight is spread across all n points such that each point has a weight of cost[i]/n.

Returns (::Vector{Point2e}, ::Vector{<: Real}).

Note

This format of data is often found in CMIE capex location data.

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Geographic utilities

We also have geographic utilities, which use e.g. Rasters.

Note

Maybe this section should be its own page, since the functionality is pretty orthogonal?

Annular rings

Karmana.annular_ring — Function

annular_ring(f, source::Raster, lon, lat, outer_radius, inner_radius; pass_mask_size = false)

Returns the result of applying f to the subset of source which is masked by the annular ring defined by lon, lat, outer_radius, inner_radius. The annular ring is constructed in geodetic space, i.e., distance is physically preserved.

source may be a 2D raster (in which case this function returns a value), or a 3D RasterStack or a RasterSeries of 2D rasters, in which case this function returns a Vector of values.

Arguments

f is a function which takes a Raster and returns a value. This is the function which will be applied to the subset of source which is masked by the constructed annular ring. The result of f is returned.
source is a Raster which will be masked by the annular ring. This can be 2D, in which case annular_ring will return a single value, or 3D, in which case annular_ring will return a Vector of values.
lon, lat are the coordinates of the centre of the annular ring, in degrees.
outer_radius and inner_radius are the outer and inner radii of the annular ring, in metres.
pass_mask_size determines whether to pass a second argument to f containing the number of points in the mask. This is useful if you are taking statistical measures.

How it works

First, an annular ring polygon is created (in geodetic space, using get_geodetic_circle).
Next, the extent of the annular ring polygon is computed, and the source raster is subsetted to that extent. This is for efficiency, and so that the minimum possible number of multiplications are performed.
The annular ring polygon is rasterized, using Rasters.boolmask.
The subsetted source raster is multiplied by the rasterized annular ring polygon.
Finally, f is applied to the result of the multiplication.

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Geodetically widened lines

Karmana.line_to_geodetic_width_poly — Function

line_to_geodetic_width_poly(line::Vector{<: Point2}, width; geodesic = Proj.geod_geodesic(6378137, 1/298.257223563))

Returns a Vector{Point2{Float64}} which represents a polygon which is width metres wide, and follows the path of line.

This is mostly useful for tracing wide lines on Raster maps.

Fundamentally, you can think of this function as creating a polygon from a line, with a specified width. There's no interpolation, though - if you want interpolation, pass an interpolated vector of points in.

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