test_median_robustness()

static void test_median_robustness ( void  )

static

Definition at line 1495 of file cu_algorithm.c.

{
        /* A simple implementation of Weiszfeld's algorithm will fail if the median is equal
         * to any one of the inputs, during any iteration of the algorithm.
         *
         * Because the algorithm uses the centroid as a starting point, this situation will
         * occur in the test case below.
         */
        do_median_test("MULTIPOINT ((0 -1), (0 0), (0 1))", "POINT (0 0)", LW_TRUE, 1000);
 
        /* Same as above but 3D, and shifter */
        do_median_test("MULTIPOINT ((1 -1 3), (1 0 2), (2 1 1))", "POINT (1 0 2)", LW_TRUE, 1000);
 
        /* Starting point is duplicated */
        do_median_test("MULTIPOINT ((0 -1), (0 0), (0 0), (0 1))", "POINT (0 0)", LW_TRUE, 1000);
 
        /* Cube */
        do_median_test("MULTIPOINT ((10 10 10), (10 20 10), (20 10 10), (20 20 10), (10 10 20), (10 20 20), (20 10 20), (20 20 20))",
                                   "POINT (15 15 15)", LW_TRUE, 1000);
 
        /* Some edge cases */
        do_median_test("POINT (7 6)", "POINT (7 6)", LW_TRUE, 1000);
        do_median_test("POINT (7 6 2)", "POINT (7 6 2)", LW_TRUE, 1000);
        do_median_test("MULTIPOINT ((7 6 2), EMPTY)", "POINT (7 6 2)", LW_TRUE, 1000);
 
        /* Empty input */
        do_median_test("MULTIPOINT EMPTY", "POINT EMPTY", LW_FALSE, 1000);
        do_median_test("MULTIPOINT (EMPTY)", "POINT EMPTY", LW_FALSE, 1000);
        do_median_test("MULTIPOINT EMPTY", "POINT EMPTY", LW_TRUE, 1000);
        do_median_test("MULTIPOINT (EMPTY)", "POINT EMPTY", LW_TRUE, 1000);
        do_median_test("MULTIPOINT ZM (1 -1 3 1, 1 0 2 7, 2 1 1 1, EMPTY)", "POINT (1 0 2)", LW_TRUE, 1000);
 
        /* Weighted input */
        do_median_test("MULTIPOINT ZM (1 -1 3 1, 1 0 2 7, 2 1 1 1)", "POINT (1 0 2)", LW_TRUE, 1000);
        do_median_test("MULTIPOINT ZM (-1 1 -3 1, -1 0 -2 7, -2 -1 -1 1)", "POINT (-1 0 -2)", LW_TRUE, 1000);
        do_median_test("MULTIPOINT ZM (-1 1 -3 1, -1 0 -2 7, -2 -1 -1 0.5, -2 -1 -1 0.5)", "POINT (-1 0 -2)", LW_TRUE, 1000);
 
        /* Point that is replaced by two half-weighted */
        do_median_test("MULTIPOINT ZM ((0 -1 0 1), (0 0 0 1), (0 1 0 0.5), (0 1 0 0.5))", "POINT (0 0 0)", LW_TRUE, 1000);
        /* Point is doubled and then erased by negative weight */
        do_median_test("MULTIPOINT ZM ((1 -1 3 1), (1 0 2 7), (2 1 1 2), (2 1 1 -1))", NULL, LW_TRUE, 1000);
        do_median_test("MULTIPOINT ZM ((1 -1 3 1), (1 0 2 7), (2 1 1 2), (2 1 1 -1))", NULL, LW_FALSE, 1000);
        /* Weightless input won't converge */
        do_median_test("MULTIPOINT ZM ((0 -1 0 0), (0 0 0 0), (0 0 0 0), (0 1 0 0))", NULL, LW_FALSE, 1000);
        do_median_test("MULTIPOINT ZM ((0 -1 0 0), (0 0 0 0), (0 0 0 0), (0 1 0 0))", NULL, LW_TRUE, 1000);
        /* Negative weight won't converge */
        do_median_test("MULTIPOINT ZM ((0 -1 0 -1), (0 0 0 -1), (0 1 0 -1))", NULL, LW_FALSE, 1000);
        do_median_test("MULTIPOINT ZM ((0 -1 0 -1), (0 0 0 -1), (0 1 0 -1))", NULL, LW_TRUE, 1000);
 
        /* Bind convergence too tightly */
        do_median_test("MULTIPOINT ((0 0), (1 1), (0 1), (2 2))", "POINT(0.75 1.0)", LW_FALSE, 0);
        do_median_test("MULTIPOINT ((0 0), (1 1), (0 1), (2 2))", NULL, LW_TRUE, 1);
        /* Unsupported geometry type */
        do_median_test("POLYGON((1 0,0 1,1 2,2 1,1 0))", NULL, LW_TRUE, 1000);
        do_median_test("POLYGON((1 0,0 1,1 2,2 1,1 0))", NULL, LW_FALSE, 1000);
 
        /* Median point is included */
        do_median_test("MULTIPOINT ZM ("
                "(1480 0 200 100),"
                "(620 0  200 100),"
                "(1000 0 -200 100),"
                "(1000 0 -590 100),"
                "(1025 0  65 100),"
                "(1025 0 -65 100)"
                ")",
        "POINT (1025 0 -65)", LW_TRUE, 10000);
 
#if 0
        /* Leads to invalid result (0 0 0) with 80bit (fmulp + faddp) precision. ok with 64 bit float ops */
        do_median_test("MULTIPOINT ZM ("
                "(0 0 20000 0.5),"
                "(0 0 59000 0.5),"
                "(0 -3000 -3472.22222222222262644208967685699462890625 1),"
                "(0  3000  3472.22222222222262644208967685699462890625 1),"
                "(0 0 -1644.736842105263121993630193173885345458984375 1),"
                "(0 0  1644.736842105263121993630193173885345458984375 1),"
                "(0  48000 -20000 1.3),"
                "(0 -48000 -20000 1.3)"
                ")",
        "POINT (0 0 0)", LW_TRUE, 10000);
#endif
 
#if 0
        /* Leads to invalid result (0 0 0) with 64bit (vfmadd231sd) precision. Ok with 80 bit float ops */
        do_median_test("MULTIPOINT ZM ("
                "(0 0 20000 0.5),"
                "(0 0 59000 0.5),"
                "(0 -3000 -3472.22222222222262644208967685699462890625 1),"
                "(0  3000  3472.22222222222262644208967685699462890625 1),"
                "(0 -0.00000000000028047739569477638384522295466033823196 -1644.736842105263121993630193173885345458984375 1),"
                "(0  0.00000000000028047739569477638384522295466033823196  1644.736842105263121993630193173885345458984375 1),"
                "(0  48000 -20000 1.3),"
                "(0 -48000 -20000 1.3)"
                ")",
        "POINT (0 0 0)", LW_TRUE, 10000);
#endif
}

References do_median_test(), LW_FALSE, and LW_TRUE.

Referenced by algorithms_suite_setup().

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