Choropleth Bin Classifier

Classify numeric map values with quantile or Jenks natural-break bins.

Description

Choropleth class breaks group numeric values into ordered map bins.

Choropleth class breaks group numeric values into ordered map bins. Quantiles target observation counts, while Jenks minimizes within-class squared variation.^[1]

Classify numeric map values with quantile or Jenks natural-break bins.

When to use Choropleth Bin Classifier

Use this tool to classify numeric map values with quantile or Jenks natural-break bins.

Prepare the text, recorded observations, aligned figures or editorial criteria requested. Confirm what each label, count, timestamp or supplied flag represents before interpreting the result.

How to use Choropleth Bin Classifier and understand its results

Prepare the text, recorded observations, aligned figures or editorial criteria requested. Confirm what each label, count, timestamp or supplied flag represents before interpreting the result.
Enter values, classCount, method using the field table and calculation rules, then run the tool.
Read breakpoints, classes. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
values	Map values	list of number	Required
classCount	Class count	integer; minimum: 1	Required
method	Classification method	string; one of "quantile", "jenks"	Required

Enter a nonempty finite-value list, integer classes 1–n and the method. Sort a copy, compute upper bounds and assign each original value to the first inclusive bound that contains it. Return bounds and zero-based class indexes in original order.

quantileBound_i=sorted[ceil((i+1)n/k)−1]; Jenks minimizes within-class SSE

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
breakpoints	Class upper bounds	list of number
classes	Zero-based classes	list of number

json

{
  "input": {
    "values": [
      1,
      2,
      3,
      100
    ],
    "classCount": 2,
    "method": "jenks"
  },
  "output": {
    "breakpoints": [
      3,
      100
    ],
    "classes": [
      0,
      0,
      0,
      1
    ]
  }
}

Limitations and assumptions

Duplicate values can create duplicate bounds or unused bins. Jenks uses O(n²k) time and O(nk) memory; use short lists. No geography, map rendering or unbiased interpretation is supplied.

Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Lists are limited to 100,000 entries; the rules above may require smaller limits. Extremely large text inputs are rejected. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Palette Contrast: Calculate color contrast and compare it with a supplied minimum. For a complementary task, use Geography Hierarchy Check: Compare caller-supplied expected and observed records for geography hierarchy check.

References

Choropleth Bin Classifier — tool.io

Similar or alternative tools

Palette Contrast
Calculate color contrast and compare it with a supplied minimum.
Geography Hierarchy Check
Compare caller-supplied expected and observed records for geography hierarchy check.