d3.thresholdSturges(values) Returns the number of bins according to Sturges’ formula; the input values must be numbers.

d3.symbolWye The Y-shape symbol type.

d3.thresholdFreedmanDiaconis(values, min, max) Returns the number of bins according to the Freedman–Diaconis rule; the input values must be numbers.

d3.symbolStar The pentagonal star (pentagram) symbol type.

d3.symbols An array containing the set of all built-in symbol types: circle, cross, diamond, square, star, triangle, and wye. Useful for constructing the range of an ordinal scale should you wish to use a shape encoding for categorical data.

d3.symbolTriangle The up-pointing triangle symbol type.

d3.symbolSquare The square symbol type.

d3.symbolCircle The circle symbol type.

d3.sum(array[, accessor]) Returns the sum of the given array of numbers. If the array is empty, returns 0. An optional accessor function may be specified, which is equivalent to calling array.map(accessor) before computing the sum. This method ignores undefined and NaN values; this is useful for ignoring missing data.

d3.symbolCross The Greek cross symbol type, with arms of equal length.