Estimates the density contours for the given array of data, returning an array of GeoJSON MultiPolygon geometry objects. Each geometry object represents the area where the estimated number of points per square pixel is greater than or equal to the corresponding threshold value; the threshold value for each geometry object is exposed as geometry.value. The returned geometry objects are typically passed to d3.geoPath to display, using null or d3.geoIdentity as the associated projection. See also d3.contours.
The x- and y-coordinate for each data point are computed using density.x and density.y. The generated contours are only accurate within the estimator’s defined size.
Array of input data.
Returns the current bandwidth, which defaults to 20.4939….
Sets the bandwidth (the standard deviation) of the Gaussian kernel and returns the density contour estimator.
Bandwidth (the standard deviation) of the Gaussian kernel. The specified bandwidth is currently rounded to the nearest supported value by this implementation, and must be nonnegative.
Returns the current cell size, which defaults to 4.
Sets the size of individual cells in the underlying bin grid to the specified positive integer and returns the density contour estimator.
The cell size is rounded down to the nearest power of two. Smaller cells produce more detailed contour polygons, but are more expensive to compute.
Cell size, a positive integer.
Returns the current size, which defaults to [960, 500].
Sets the size of the density estimator to the specified bounds and returns the density contour estimator.
The size is specified as an array [width, height], where width is the maximum x-value and height is the maximum y-value.
Returns the current threshold generator, which by default generates about twenty nicely-rounded density thresholds.
Sets the threshold generator to the specified function or array and returns this contour generator. Thresholds are defined as an array of values [x0, x1, …]. The first generated density contour corresponds to the area where the estimated density is greater than or equal to x0; the second contour corresponds to the area where the estimated density is greater than or equal to x1, and so on. Thus, there is exactly one generated MultiPolygon geometry object for each specified threshold value; the threshold value is exposed as geometry.value. The first value x0 should typically be greater than zero. If a count is specified instead of an array of thresholds, then approximately count uniformly-spaced nicely-rounded thresholds will be generated; see d3.ticks.
Returns the current point weight accessor.
Returns the current point weight accessor.
Sets the point weight accessor and returns the density contour estimator.
A point weight accessor function.
Returns the current x-coordinate accessor. The default x-coordinate accessor is a functions which accepts as input a two-element array of numbers and returns the element at index 0.
Returns the current x-coordinate accessor. The default x-coordinate accessor is a functions which accepts as input a two-element array of numbers and returns the element at index 0.
Sets the x-coordinate accessor and returns the density contour estimator.
An x-coordinate accessor function, which accepts as input an element of the input data array and returns the x-coordinate.
Returns the current y-coordinate accessor. The default y-coordinate accessor is a functions which accepts as input a two-element array of numbers and returns the element at index 1.
Returns the current y-coordinate accessor. The default y-coordinate accessor is a functions which accepts as input a two-element array of numbers and returns the element at index 1.
Sets the y-coordinate accessor and returns the density contour estimator.
An y-coordinate accessor function, which accepts as input an element of the input data array and returns the y-coordinate.
A contour generator for density estimates.
The generic refers to the data type of an element in the data array used with the density contour generator. If omitted, the default setting assumes that, the elements of the data array used with the density contour generator are two-element arrays. The first element corresponds to the x-dimension, the second to the y-dimension.