Sliding Window Distinct Count

Count distinct exact-string values in each complete stride-one window, preserving window order.

Description

Count distinct exact-string values in each complete stride-one window, preserving window order.

A sliding distinct count measures local variety within a fixed-width window. Repeated entries contribute once within each window, even when they are nonadjacent.

When to use this tool

Count distinct exact-string values in each complete stride-one window, preserving window order.

Prepare the supplied values, window fields for this operation.
Compare the complete example with the representation used by your own input before carrying the result into another step.

How to use the tool and how it works

Enter values, window. Use the exact text syntax, units and index conventions explained below.
Run the tool. If input validation fails, correct the supplied fields before interpreting any result.
Read result.counts. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.

For every complete consecutive window, construct a Set of its values and return the set size in window-start order. Require window from one through 128.^[1]

Input field	Meaning and representation	Accepted input
values	values.	At most 128 strings, each at most 128 UTF-16 code units
window	window.	Integer from 1 to 128 inclusive

Output field	Interpretation
result	Object containing the named outputs below.
result.counts	The counts list in the ordering and representation described above.

json

{
  "input": {
    "values": [
      "a",
      "a",
      "b",
      "a"
    ],
    "window": 3
  },
  "output": {
    "result": {
      "counts": [
        2,
        2
      ]
    }
  }
}

Limitations and assumptions

The tool returns counts rather than the distinct members. A window longer than the list produces an empty output; partial windows and locale-aware string comparisons are not used.
Every declared top-level field is required and unexpected fields are rejected. Numeric inputs must be finite; ordinary text fields are bounded to 8,192 UTF-16 code units, with tighter operation-specific limits where stated.
Ordinary string lists have at most 128 entries of at most 128 code units each; numeric lists and matrices have separate bounded size checks. Nonfinite results and excessively large serialized outputs are rejected.
Indexes are zero-based and spans have an exclusive end unless explicitly stated otherwise. A valid false, null or empty-list result is distinct from malformed input.

Alternative or Complementary methods

Use explicit source-index maps when rearranging data or planning missing-value fills. Keep row-major coordinates, cyclic indexes and one-based occurrence numbers distinct, and inspect null donor positions before copying values.

References

Tool behavior and example: Sliding Window Distinct Count — tool.io

Similar or alternative tools

sliding window
Slice a list into overlapping fixed-size windows stepped one element at a time.
Sliding Window Transition Count
Count adjacent value transitions in each complete stride-one window, preserving window order.