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Flip y-coordinates for spatial data objects

Source: R/spatialplot.R
dot_flip_y.Rd

These internal S3 methods flip the y-coordinates of SpatRaster, SpatVector, and data.frame objects.

For rasters, the raster is flipped vertically and its extent is negated. For vectors, the y-coordinates of all geometries are negated. For data frames, the specified y column is negated.

Usage

.flip_y(data, ...)

# S3 method for class 'SpatRaster'
.flip_y(data, ...)

# S3 method for class 'SpatVector'
.flip_y(data, ...)

# S3 method for class 'data.frame'
.flip_y(data, y = "y", ...)

Arguments

data

A SpatRaster, SpatVector, or data.frame.

...

Additional arguments (not used).

y

A character string specifying the y column name for data.frame input. Ignored for SpatRaster and SpatVector. Default is "y".

Value

For SpatRaster input, a SpatRaster flipped vertically with negated y-extent. For SpatVector input, a SpatVector with negated y-coordinates. For data.frame input, a data frame with the specified y column negated.

Details

These functions are intended for internal use to facilitate coordinate transformations. When visualizing spatial data, it is often necessary to flip the y-axis to put the origin at the top-left corner. However, geom_sf() does not work with scale_y_reverse(). See this GitHub comment for details. These functions negate the y-coordinates so that the axis labels can be displayed with reversed sign, mimicking scale_y_reverse().