;============================================================
;   iron_dbscan.hsp — DBSCAN 密度ベースクラスタリング
;
;   Ester et al. の密度ベース。eps 半径以内の近傍点数が min_pts 以上なら
;   core、それ以外で core に到達できるなら border、残りが noise (-1)。
;   任意形状のクラスタ検出 + 外れ値抽出。
;   inline C# (O(n²) ブルートフォース近傍検索)。中規模 (~5000 点) まで。
;
;   API:
;     dbscan_fit X, n, n_feat, eps, min_pts
;     dbscan_labels array v_labels, int n        → 各点のクラスタ id (noise=-1)
;     dbscan_cluster_count                         → stat=クラスタ数
;     dbscan_noise_count                           → stat=外れ値数
;     dbscan_release
;============================================================
#ifndef __iron_dbscan_hsp__
#define __iron_dbscan_hsp__

#module iron_dbscan

dim _db_cs_loaded, 1

#deffunc _db_load_cs
	if _db_cs_loaded : return
	sdim _cs, 16384
	_cs = {"
using System;
using System.Collections.Generic;
using System.Text;

public class HspDBSCAN {
    static int[] labels;
    static int nCluster = 0;

    public static string Fit(double[] X, int n, int f, double eps, int minPts) {
        labels = new int[n];
        for (int i = 0; i < n; i++) labels[i] = -2;   // -2 = unvisited
        double eps2 = eps * eps;
        int cid = 0;
        for (int i = 0; i < n; i++) {
            if (labels[i] != -2) continue;
            var neighbors = RegionQuery(X, n, f, i, eps2);
            if (neighbors.Count < minPts) {
                labels[i] = -1;   // noise
                continue;
            }
            labels[i] = cid;
            var seeds = new Queue<int>(neighbors);
            while (seeds.Count > 0) {
                int q = seeds.Dequeue();
                if (labels[q] == -1) labels[q] = cid;
                if (labels[q] != -2) continue;
                labels[q] = cid;
                var qNeighbors = RegionQuery(X, n, f, q, eps2);
                if (qNeighbors.Count >= minPts) {
                    foreach (var p in qNeighbors) seeds.Enqueue(p);
                }
            }
            cid++;
        }
        nCluster = cid;
        return \"0\";
    }
    static List<int> RegionQuery(double[] X, int n, int f, int i, double eps2) {
        var r = new List<int>();
        for (int j = 0; j < n; j++) {
            if (j == i) continue;
            double d = 0;
            for (int k = 0; k < f; k++) { double dd = X[i * f + k] - X[j * f + k]; d += dd * dd; }
            if (d <= eps2) r.Add(j);
        }
        r.Add(i);
        return r;
    }
    public static string Labels() {
        var sb = new StringBuilder();
        for (int i = 0; i < labels.Length; i++) { if (i > 0) sb.Append('\\t'); sb.Append(labels[i]); }
        return sb.ToString();
    }
    public static int ClusterCount() { return nCluster; }
    public static int NoiseCount() {
        int c = 0; for (int i = 0; i < labels.Length; i++) if (labels[i] == -1) c++;
        return c;
    }
    public static string Release() { labels = null; nCluster = 0; return \"0\"; }
}
"}
	loadnet _cs, 3
	_db_cs_loaded = 1
	return

#deffunc _db_parse_i str tsv, array v, int expected, \
	local _p, local _tab, local _i
	dim v, expected
	_p = 0 : _i = 0
	repeat
		_tab = instr(tsv, _p, "\t")
		if _tab < 0 {
			if _i < expected : v(_i) = int(strmid(tsv, _p, strlen(tsv) - _p))
			break
		}
		if _i < expected : v(_i) = int(strmid(tsv, _p, _tab - _p))
		_p = _tab + 1
		_i++
	loop
	return

#deffunc dbscan_fit array X, int n, int n_feat, double eps, int min_pts, \
	local _h, local _r
	_db_load_cs
	newnet _h, "HspDBSCAN"
	mcall _h, "Fit", _r, X, n, n_feat, eps, min_pts
	return int("" + _r)

#deffunc dbscan_labels array v_labels, int n, \
	local _h, local _r, local _tsv
	_db_load_cs
	newnet _h, "HspDBSCAN"
	mcall _h, "Labels", _r
	_tsv = "" + _r
	_db_parse_i _tsv, v_labels, n
	return 0

#defcfunc dbscan_cluster_count \
	local _h, local _r
	_db_load_cs
	newnet _h, "HspDBSCAN"
	mcall _h, "ClusterCount", _r
	return int("" + _r)

#defcfunc dbscan_noise_count \
	local _h, local _r
	_db_load_cs
	newnet _h, "HspDBSCAN"
	mcall _h, "NoiseCount", _r
	return int("" + _r)

#deffunc dbscan_release \
	local _h, local _r
	_db_load_cs
	newnet _h, "HspDBSCAN"
	mcall _h, "Release", _r
	return 0

#global
#endif