R中的K最短路径：igraph答案

【问题标题】：K Shortest Path in R: igraphR中的K最短路径：igraph
【发布时间】：2015-08-14 05:48:20
【问题描述】：

我必须找到 K 最短路径，但是当我选择不同的 K 值并且计算的距离不正确时，我尝试的以下代码给出了相同的路径。

我的数据集是my.graph，类igraph

dput(my.graph)
    structure(list(169, FALSE, c(22, 1, 2, 1, 2, 3, 114, 3, 4, 5, 
    4, 5, 6, 6, 7, 7, 8, 9, 8, 110, 78, 159, 9, 159, 30, 11, 13, 
    160, 11, 66, 160, 138, 14, 13, 14, 15, 81, 16, 15, 17, 16, 17, 
    18, 18, 19, 130, 19, 62, 62, 23, 42, 22, 22, 22, 23, 24, 161, 
    24, 25, 25, 26, 64, 26, 28, 161, 29, 28, 29, 47, 48, 53, 142, 
    31, 30, 32, 31, 32, 33, 33, 34, 35, 118, 34, 36, 35, 37, 36, 
    37, 38, 39, 38, 162, 40, 39, 40, 41, 41, 42, 43, 44, 43, 44, 
    45, 45, 46, 47, 46, 47, 47, 49, 48, 49, 50, 51, 50, 52, 51, 52, 
    53, 60, 53, 54, 53, 55, 54, 56, 55, 57, 56, 57, 58, 58, 59, 59, 
    60, 60, 60, 63, 162, 62, 62, 63, 64, 65, 65, 66, 166, 68, 163, 
    164, 69, 165, 68, 70, 69, 71, 70, 71, 72, 72, 73, 112, 73, 74, 
    75, 74, 76, 75, 76, 77, 78, 77, 78, 110, 78, 79, 80, 79, 146, 
    80, 81, 82, 81, 81, 82, 137, 164, 84, 85, 84, 86, 85, 86, 87, 
    87, 164, 165, 89, 89, 90, 90, 91, 92, 91, 93, 92, 93, 94, 95, 
    94, 165, 95, 163, 97, 97, 98, 99, 98, 99, 100, 101, 100, 101, 
    102, 102, 163, 104, 166, 105, 104, 106, 105, 106, 107, 108, 107, 
    109, 108, 109, 166, 110, 110, 125, 116, 112, 113, 112, 112, 114, 
    113, 114, 115, 114, 126, 115, 116, 117, 118, 117, 119, 118, 118, 
    120, 119, 120, 121, 121, 122, 123, 122, 124, 168, 141, 123, 124, 
    125, 125, 125, 126, 140, 140, 128, 128, 129, 130, 129, 130, 130, 
    131, 131, 132, 133, 132, 134, 133, 134, 135, 135, 136, 137, 136, 
    137, 137, 139, 138, 139, 168, 143, 140, 140, 141, 142, 158, 167, 
    143, 167, 144, 145, 144, 145, 146, 146, 146, 148, 148, 149, 149, 
    150, 151, 150, 152, 151, 153, 152, 153, 154, 154, 155, 156, 155, 
    156, 157, 157, 158, 158, 158, 159, 160, 159, 160, 160, 160, 161, 
    161, 162, 162, 163, 163, 163, 164, 164, 164, 165, 165, 165, 166, 
    166, 166, 167, 167, 168, 168), c(0, 0, 1, 0, 1, 2, 2, 2, 3, 4, 
    3, 4, 5, 5, 6, 6, 7, 8, 7, 9, 9, 9, 8, 10, 10, 10, 11, 11, 10, 
    12, 12, 12, 13, 11, 13, 14, 14, 15, 14, 16, 15, 16, 17, 17, 18, 
    19, 18, 19, 20, 20, 21, 21, 0, 21, 20, 23, 23, 23, 24, 24, 25, 
    26, 25, 27, 27, 28, 27, 28, 29, 29, 29, 30, 30, 10, 31, 30, 31, 
    32, 32, 33, 34, 34, 33, 35, 34, 36, 35, 36, 37, 38, 37, 38, 39, 
    38, 39, 40, 40, 21, 42, 43, 42, 43, 44, 44, 45, 46, 45, 29, 46, 
    48, 29, 48, 49, 50, 49, 51, 50, 51, 52, 53, 52, 53, 29, 54, 53, 
    55, 54, 56, 55, 56, 57, 57, 58, 58, 59, 53, 59, 61, 61, 20, 19, 
    61, 26, 64, 64, 12, 67, 67, 67, 68, 68, 68, 67, 69, 68, 70, 69, 
    70, 71, 71, 72, 72, 72, 73, 74, 73, 75, 74, 75, 76, 77, 76, 77, 
    78, 9, 78, 79, 78, 80, 79, 80, 81, 80, 14, 81, 82, 83, 83, 84, 
    83, 85, 84, 85, 86, 86, 87, 88, 88, 88, 89, 89, 90, 91, 90, 92, 
    91, 92, 93, 94, 93, 95, 94, 96, 96, 96, 97, 98, 97, 98, 99, 100, 
    99, 100, 101, 101, 102, 103, 103, 104, 103, 105, 104, 105, 106, 
    107, 106, 108, 107, 108, 109, 9, 78, 110, 111, 111, 112, 72, 
    111, 113, 112, 113, 114, 2, 115, 114, 111, 116, 117, 116, 118, 
    117, 34, 119, 118, 119, 120, 120, 121, 122, 121, 123, 123, 123, 
    122, 123, 124, 124, 110, 115, 126, 127, 127, 127, 128, 129, 128, 
    129, 19, 130, 130, 131, 132, 131, 133, 132, 133, 134, 134, 135, 
    136, 135, 136, 82, 138, 12, 138, 139, 139, 127, 126, 123, 30, 
    142, 142, 139, 143, 143, 144, 143, 144, 145, 80, 145, 147, 147, 
    148, 148, 149, 150, 149, 151, 150, 152, 151, 152, 153, 153, 154, 
    155, 154, 155, 156, 156, 157, 142, 157, 9, 159, 10, 12, 11, 159, 
    23, 27, 61, 38, 96, 67, 102, 68, 83, 87, 95, 88, 68, 67, 109, 
    103, 142, 143, 123, 139), c(3, 1, 4, 2, 7, 5, 10, 8, 11, 9, 13, 
    12, 15, 14, 18, 16, 22, 17, 28, 25, 33, 26, 34, 32, 38, 35, 40, 
    37, 41, 39, 43, 42, 46, 44, 52, 0, 53, 51, 54, 49, 57, 55, 59, 
    58, 62, 60, 66, 63, 67, 65, 73, 24, 75, 72, 76, 74, 78, 77, 82, 
    79, 84, 80, 86, 83, 87, 85, 90, 88, 93, 89, 94, 92, 96, 95, 97, 
    50, 100, 98, 101, 99, 103, 102, 106, 104, 107, 68, 108, 105, 
    110, 69, 111, 109, 114, 112, 116, 113, 117, 115, 122, 70, 120, 
    118, 124, 121, 126, 123, 128, 125, 129, 127, 131, 130, 133, 132, 
    135, 119, 136, 134, 140, 47, 139, 48, 141, 137, 142, 61, 144, 
    143, 145, 29, 152, 147, 154, 150, 156, 153, 157, 155, 159, 158, 
    162, 160, 165, 163, 167, 164, 168, 166, 171, 169, 174, 20, 172, 
    170, 177, 175, 179, 176, 183, 36, 182, 180, 184, 181, 189, 187, 
    191, 188, 192, 190, 194, 193, 198, 197, 200, 199, 203, 201, 205, 
    202, 206, 204, 209, 207, 211, 208, 214, 213, 217, 215, 218, 216, 
    221, 219, 222, 220, 224, 223, 229, 226, 231, 228, 232, 230, 235, 
    233, 237, 234, 238, 236, 240, 19, 241, 173, 246, 161, 247, 244, 
    249, 245, 252, 6, 250, 248, 254, 251, 255, 243, 258, 256, 261, 
    81, 260, 257, 263, 259, 264, 262, 266, 265, 269, 267, 273, 268, 
    274, 270, 277, 242, 276, 275, 278, 253, 282, 281, 285, 283, 287, 
    45, 286, 284, 289, 288, 292, 290, 294, 291, 295, 293, 297, 296, 
    300, 298, 302, 185, 301, 299, 304, 31, 305, 303, 309, 279, 308, 
    280, 310, 272, 311, 71, 314, 307, 318, 316, 319, 317, 321, 178, 
    322, 320, 324, 323, 326, 325, 329, 327, 331, 328, 333, 330, 334, 
    332, 336, 335, 339, 337, 340, 338, 342, 341, 344, 312, 345, 343, 
    346, 21, 348, 23, 350, 27, 349, 30, 351, 347, 352, 56, 353, 64, 
    355, 91, 354, 138, 357, 148, 356, 212, 358, 225, 359, 149, 360, 
    186, 361, 195, 364, 151, 363, 196, 362, 210, 365, 146, 367, 227, 
    366, 239, 368, 313, 369, 315, 370, 271, 371, 306), c(3, 1, 52, 
    0, 4, 2, 7, 5, 252, 6, 10, 8, 11, 9, 13, 12, 15, 14, 18, 16, 
    22, 17, 174, 20, 240, 19, 346, 21, 28, 25, 73, 24, 348, 23, 33, 
    26, 350, 27, 145, 29, 304, 31, 349, 30, 34, 32, 38, 35, 183, 
    36, 40, 37, 41, 39, 43, 42, 46, 44, 140, 47, 287, 45, 54, 49, 
    139, 48, 53, 51, 97, 50, 57, 55, 352, 56, 59, 58, 62, 60, 142, 
    61, 66, 63, 353, 64, 67, 65, 107, 68, 110, 69, 122, 70, 75, 72, 
    311, 71, 76, 74, 78, 77, 82, 79, 84, 80, 261, 81, 86, 83, 87, 
    85, 90, 88, 93, 89, 355, 91, 94, 92, 96, 95, 100, 98, 101, 99, 
    103, 102, 106, 104, 108, 105, 111, 109, 114, 112, 116, 113, 117, 
    115, 120, 118, 124, 121, 135, 119, 126, 123, 128, 125, 129, 127, 
    131, 130, 133, 132, 136, 134, 141, 137, 354, 138, 144, 143, 152, 
    147, 357, 148, 365, 146, 154, 150, 359, 149, 364, 151, 156, 153, 
    157, 155, 159, 158, 162, 160, 246, 161, 165, 163, 167, 164, 168, 
    166, 171, 169, 172, 170, 177, 175, 241, 173, 179, 176, 182, 180, 
    321, 178, 184, 181, 302, 185, 189, 187, 360, 186, 191, 188, 192, 
    190, 194, 193, 361, 195, 198, 197, 363, 196, 200, 199, 203, 201, 
    205, 202, 206, 204, 209, 207, 211, 208, 362, 210, 214, 213, 356, 
    212, 217, 215, 218, 216, 221, 219, 222, 220, 224, 223, 358, 225, 
    229, 226, 367, 227, 231, 228, 232, 230, 235, 233, 237, 234, 238, 
    236, 366, 239, 277, 242, 247, 244, 255, 243, 249, 245, 250, 248, 
    254, 251, 278, 253, 258, 256, 260, 257, 263, 259, 264, 262, 266, 
    265, 269, 267, 273, 268, 274, 270, 310, 272, 370, 271, 276, 275, 
    309, 279, 282, 281, 308, 280, 285, 283, 286, 284, 289, 288, 292, 
    290, 294, 291, 295, 293, 297, 296, 300, 298, 301, 299, 305, 303, 
    314, 307, 371, 306, 344, 312, 368, 313, 318, 316, 369, 315, 319, 
    317, 322, 320, 324, 323, 326, 325, 329, 327, 331, 328, 333, 330, 
    334, 332, 336, 335, 339, 337, 340, 338, 342, 341, 345, 343, 351, 
    347), c(0, 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 18, 20, 20, 22, 
    24, 26, 28, 30, 32, 34, 34, 34, 38, 40, 42, 44, 46, 46, 48, 50, 
    52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 
    84, 88, 90, 92, 94, 96, 98, 102, 104, 106, 108, 110, 112, 114, 
    118, 118, 122, 124, 126, 128, 130, 130, 132, 134, 136, 138, 140, 
    142, 144, 146, 148, 150, 154, 156, 158, 162, 164, 164, 166, 168, 
    170, 172, 172, 174, 176, 178, 180, 182, 184, 186, 186, 188, 190, 
    192, 194, 196, 198, 198, 200, 202, 204, 206, 208, 210, 214, 214, 
    218, 220, 224, 226, 228, 230, 234, 236, 238, 240, 242, 244, 246, 
    250, 252, 252, 254, 256, 260, 262, 264, 266, 268, 270, 272, 276, 
    278, 280, 284, 286, 288, 290, 292, 294, 298, 298, 300, 302, 304, 
    306, 308, 310, 312, 314, 316, 318, 322, 326, 332, 336, 340, 346, 
    352, 358, 364, 368, 372), c(0, 4, 6, 10, 12, 14, 16, 18, 20, 
    22, 28, 34, 38, 44, 46, 50, 52, 54, 56, 58, 62, 66, 70, 70, 74, 
    76, 78, 80, 84, 86, 92, 96, 98, 100, 102, 106, 108, 110, 112, 
    116, 118, 120, 120, 122, 124, 126, 128, 130, 130, 132, 134, 136, 
    138, 140, 144, 146, 148, 150, 152, 154, 156, 156, 160, 160, 160, 
    162, 162, 162, 168, 174, 176, 178, 180, 184, 186, 188, 190, 192, 
    194, 198, 200, 204, 206, 208, 212, 214, 216, 218, 220, 224, 226, 
    228, 230, 232, 234, 236, 238, 242, 244, 246, 248, 250, 252, 254, 
    258, 260, 262, 264, 266, 268, 270, 272, 276, 278, 280, 282, 284, 
    286, 288, 290, 292, 294, 296, 298, 304, 306, 306, 308, 312, 314, 
    316, 318, 320, 322, 324, 326, 328, 330, 330, 332, 336, 336, 336, 
    340, 344, 346, 348, 348, 350, 352, 354, 356, 358, 360, 362, 364, 
    366, 368, 370, 370, 372, 372, 372, 372, 372, 372, 372, 372, 372, 
    372), list(c(1, 0, 1), structure(list(), .Names = character(0)), 
        structure(list(name = c("1", "2", "3", "4", "5", "6", "7", 
        "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", 
        "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", 
        "28", "29", "30", "31", "32", "33", "34", "35", "36", "37", 
        "38", "39", "40", "41", "42", "43", "44", "45", "46", "47", 
        "48", "49", "50", "51", "52", "53", "54", "55", "56", "57", 
        "58", "59", "60", "61", "62", "63", "64", "65", "66", "67", 
        "68", "69", "70", "71", "72", "73", "74", "75", "76", "77", 
        "78", "79", "80", "81", "82", "83", "84", "85", "86", "87", 
        "88", "89", "90", "91", "92", "93", "94", "95", "96", "97", 
        "98", "99", "100", "101", "102", "103", "104", "105", "106", 
        "107", "108", "109", "110", "111", "112", "113", "114", "115", 
        "116", "117", "118", "119", "120", "121", "122", "123", "124", 
        "125", "126", "127", "128", "129", "130", "131", "132", "133", 
        "134", "135", "136", "137", "138", "139", "140", "141", "142", 
        "143", "144", "145", "146", "147", "148", "149", "150", "151", 
        "152", "153", "154", "155", "156", "157", "158", "159", "160", 
        "161", "162", "163", "164", "165", "166", "167", "168", "169"
        )), .Names = "name"), structure(list(DIST_KM_CNT = c(4.89, 
        1.45, 2.36, 1.45, 2.36, 1.18, 0, 1.18, 0.89, 1.47, 0.89, 
        1.47, 1.16, 1.16, 1.2, 1.2, 1.02, 0.79, 1.02, 0, 0, 1, 0.79, 
        0, 0.98, 1.03, 1.15, 0, 1.03, 1.35, 0.95, 0, 0.99, 1.15, 
        0.99, 1.53, 0, 1.22, 1.53, 1.37, 1.22, 1.37, 1.23, 1.23, 
        1.1, 0, 1.1, 1.38, 1.69, 3.49, 3.16, 1.38, 4.89, 1.38, 3.49, 
        1.51, 0, 1.51, 1.39, 1.39, 1.78, 0.947, 1.78, 1.17, 2.12, 
        3.26, 1.17, 3.26, 1.43, 0, 0, 15.58, 1.11, 0.98, 1.09, 1.11, 
        1.09, 1.43, 1.43, 1.15, 1.11, 0, 1.15, 1.13, 1.11, 1.96, 
        1.13, 1.96, 1.86, 2.48, 1.86, 0, 1.44, 2.48, 1.44, 2.38, 
        2.38, 3.16, 2.41, 1.691, 2.41, 1.691, 1.54, 1.54, 1.65, 4.14, 
        1.65, 1.43, 4.14, 0.572, 0, 0.572, 0.455, 0.558, 0.455, 0.54, 
        0.558, 0.54, 0.682, 0.638, 0.682, 0.42, 0, 0.624, 0.42, 0.47, 
        0.624, 0.895, 0.47, 0.895, 0.493, 0.493, 0.703, 0.703, 0.553, 
        0.638, 0.553, 4.52, 1.94, 1.69, 1.38, 4.52, 0.947, 2.647, 
        2.647, 1.35, 0, 1.66, 0, 0, 1.05, 0, 1.66, 1.31, 1.05, 1.54, 
        1.31, 1.54, 1.72, 1.72, 1.24, 0, 1.24, 0.94, 1.57, 0.94, 
        1.15, 1.57, 1.15, 0.77, 0.95, 0.77, 0.95, 0, 0, 1.38, 0.6, 
        1.38, 11.42, 0.6, 0.72, 2.64, 0.72, 0, 2.64, 0, 0.82, 0.708, 
        0.467, 0.708, 0.59, 0.467, 0.59, 0.828, 0.828, 1.047, 0.77, 
        0.517, 0.517, 0.897, 0.897, 0.727, 0.602, 0.727, 0.481, 0.602, 
        0.481, 0.726, 0.602, 0.726, 0.92, 0.602, 0.986, 0.44, 0.44, 
        0.513, 0.548, 0.513, 0.548, 0.721, 0.513, 0.721, 0.513, 0.564, 
        0.564, 0.937, 0.412, 0.576, 0.542, 0.412, 0.567, 0.542, 0.567, 
        0.497, 0.426, 0.497, 0.379, 0.426, 0.379, 0.987, 0, 0, 0.614, 
        1.321, 1.327, 0.912, 0, 1.327, 1.735, 0.912, 1.735, 1.577, 
        0, 1.188, 1.577, 1.321, 1.017, 1.057, 1.017, 1.239, 1.057, 
        0, 0.732, 1.239, 0.732, 0.877, 0.877, 1.548, 0.816, 1.548, 
        0.806, 0, 11.5, 0.816, 0.806, 0.689, 0.689, 0.614, 1.188, 
        1.357, 2.496, 1.028, 1.028, 1.432, 0.93, 1.432, 0.93, 0, 
        0.794, 0.794, 0.811, 1.395, 0.811, 1.323, 1.395, 1.323, 1.385, 
        1.385, 0.774, 1.53, 0.774, 1.53, 0, 0.841, 0, 0.841, 1.317, 
        7.75, 2.496, 1.357, 11.5, 15.58, 0.75, 0.905, 7.75, 1.317, 
        0.89, 0.593, 0.89, 0.593, 0.555, 11.42, 0.555, 1.18, 1.18, 
        0.87, 0.87, 2.63, 1.21, 2.63, 1.6, 1.21, 1.26, 1.6, 1.26, 
        1.09, 1.09, 1.12, 1.58, 1.12, 1.58, 1.42, 1.42, 0.54, 0.75, 
        0.54, 1, 1.03, 0, 0.95, 0, 1.03, 0, 2.12, 1.94, 0, 0.986, 
        0, 0.937, 0, 0.82, 1.047, 0.92, 0.77, 0, 0, 0.987, 0.576, 
        0.905, 1.317, 0, 1.317)), .Names = "DIST_KM_CNT")), <environment>), class = "igraph")

K 最短路径逻辑

# find k shortest paths
k.shortest.paths <- function(graph, from, to, k){
  # first shortest path
  k0 <- get.shortest.paths(graph,from,to, output='both')

  # number of currently found shortest paths
  kk <- 1

  # list of alternatives
  variants <- list()

  # shortest variants
  shortest.variants <- list(list(g=graph, path=k0$epath, vert=k0$vpath, dist=shortest.paths(graph,from,to)))

  # until k shortest paths are found
  while(kk<k){
    # take last found shortest path
    last.variant <- shortest.variants[[length(shortest.variants)]]              

    # calculate all alternatives
    variants <- calculate.variants(variants, last.variant, from, to)

    # find shortest alternative
    sp <- select.shortest.path(variants)

    # add to list, increase kk, remove shortest path from list of alternatives
    shortest.variants[[length(shortest.variants)+1]] <- list(g=variants[[sp]]$g, path=variants[[sp]]$variants$path, vert=variants[[sp]]$variants$vert, dist=variants[[sp]]$variants$dist)
    kk <- kk+1
    variants <- variants[-sp]
  }

  return(shortest.variants)
}

# found all alternative routes
calculate.variants <- function(variants, variant, from, to){
  # take graph from current path
  g <- variant$g

  # iterate through edges, removing one each iterations
  for (j in unlist(variant$path)){
    newgraph <- delete.edges(g, j) # remove adge
    sp <- get.shortest.paths(newgraph,from,to, output='both') # calculate shortest path
    spd <- shortest.paths(newgraph,from,to) # calculate length
    if (spd != Inf){ # the the path is found
      if (!contains.path(variants, sp$vpath)) # add to list, unless it already contains the same path
      {
        variants[[length(variants)+1]] <- list(g=newgraph, variants=list(path=sp$epath, vert=sp$vpath, dist=spd))
      }
    }
  }

  return(variants)
}

# does a list contain this path?
contains.path <- function(variants, variant){
  return( any( unlist( lapply( variants, function(x){ identical(x$variant$vert,variant) } ) ) ) )
}

# which path from the list is the shortest?
select.shortest.path <- function(variants){
  return( which.min( unlist( lapply( variants, function(x){x$variants$dist} ) ) ) )
}

结果如下，路径相同，计算的距离也不正确。我不确定我在哪里犯了错误

library(igraph)
k.shortest.paths(my.graph, from = 37, to = 8, k = 2)

[[1]]
[[1]]$g
IGRAPH UN-- 169 372 -- 
+ attr: name (v/c), DIST_KM_CNT (e/n)
+ edges (vertex names):
 [1] 1 --23  1 --2   2 --3   1 --2   2 --3   3 --4   3 --115 3 --4   4 --5  
[10] 5 --6   4 --5   5 --6   6 --7   6 --7   7 --8   7 --8   8 --9   9 --10 
[19] 8 --9   10--111 10--79  10--160 9 --10  11--160 11--31  11--12  12--14 
[28] 12--161 11--12  13--67  13--161 13--139 14--15  12--14  14--15  15--16 
[37] 15--82  16--17  15--16  17--18  16--17  17--18  18--19  18--19  19--20 
[46] 20--131 19--20  20--63  21--63  21--24  22--43  22--23  1 --23  22--23 
[55] 21--24  24--25  24--162 24--25  25--26  25--26  26--27  27--65  26--27 
[64] 28--29  28--162 29--30  28--29  29--30  30--48  30--49  30--54  31--143
+ ... omitted several edges

[[1]]$path
[[1]]$path[[1]]
+ 11/372 edges (vertex names):
 [1] 36--37  35--36  34--35  33--34  32--33  31--32  11--31  11--160 10--160
[10] 9 --10  8 --9  


[[1]]$vert
[[1]]$vert[[1]]
+ 12/169 vertices, named:
 [1] 37  36  35  34  33  32  31  11  160 10  9   8  


[[1]]$dist
    8
37 11


[[2]]
[[2]]$g
IGRAPH UN-- 169 371 -- 
+ attr: name (v/c), DIST_KM_CNT (e/n)
+ edges (vertex names):
 [1] 1 --23  1 --2   2 --3   1 --2   2 --3   3 --4   3 --115 3 --4   4 --5  
[10] 5 --6   4 --5   5 --6   6 --7   6 --7   7 --8   7 --8   8 --9   9 --10 
[19] 8 --9   10--111 10--79  10--160 9 --10  11--160 11--31  11--12  12--14 
[28] 12--161 11--12  13--67  13--161 13--139 14--15  12--14  14--15  15--16 
[37] 15--82  16--17  15--16  17--18  16--17  17--18  18--19  18--19  19--20 
[46] 20--131 19--20  20--63  21--63  21--24  22--43  22--23  1 --23  22--23 
[55] 21--24  24--25  24--162 24--25  25--26  25--26  26--27  27--65  26--27 
[64] 28--29  28--162 29--30  28--29  29--30  30--48  30--49  30--54  31--143
+ ... omitted several edges

[[2]]$path
[[2]]$path[[1]]
+ 11/371 edges (vertex names):
 [1] 36--37  35--36  34--35  33--34  32--33  31--32  11--31  11--160 10--160
[10] 9 --10  8 --9  


[[2]]$vert
[[2]]$vert[[1]]
+ 12/169 vertices, named:
 [1] 37  36  35  34  33  32  31  11  160 10  9   8  


[[2]]$dist
    8
37 11

【问题讨论】：

如果您发布 minimal example 来说明您正在尝试做的事情，而不是使用整个数据集，您将更有可能获得答案。
@Bryan 数据集有 342 行和 3 列。这是精简后的数据集
这可能是一个精简的数据集，但最好使用最小的数据集。什么是问题的最简单版本，它仍然能够捕捉到您要解决的问题的相关元素？此外，除了使用dput 转储igraph 对象之外，您还可以提供更多上下文，例如，从一些边缘和节点的宽度开始创建igraph 对象。这将帮助其他人从您正在尝试做的事情中学习，并使答案更加普遍。最后，说出“不正确”的意思。你怎么知道它不正确以及你期望什么？
如何查看链接权重的总和？？！结果只显示了 [[1]]$g、[[1]]$path、[[1]]$vert 和 [[1]]$dist。 [[1]]$dist 仅显示节点数。我想将值乘以权重。！！谢谢

标签： r igraph shortest-path

【解决方案1】：

我知道这已经晚了 2 年，但希望这对需要在 R 中实现日元算法的其他人有用。

library(igraph)
library(tidyverse)

#'@return the shortest path as a list of vertices or NULL if there is no path between src and dest
shortest_path <- function(graph, src, dest){
  path <- suppressWarnings(get.shortest.paths(graph, src, dest))
  path <- names(path$vpath[[1]])
  if (length(path)==1) NULL else path
} 

#'@return the sum of the weights of all the edges in the given path
path_weight <- function(path, graph) sum(E(graph, path=path)$weight)

#'@description sorts a list of paths based on the weight of the path
sort_paths <- function(graph, paths) paths[paths %>% sapply(path_weight, graph) %>% order]

#'@description creates a list of edges that should be deleted
find_edges_to_delete <- function(A,i,rootPath){
  edgesToDelete <- NULL
  for (p in A){
    rootPath_p <- p[1:i]
    if (all(rootPath_p == rootPath)){
      edge <- paste(p[i], ifelse(is.na(p[i+1]),p[i],p[i+1]), sep = '|')
      edgesToDelete[length(edgesToDelete)+1] <- edge
    }
  }
  unique(edgesToDelete)
}

#returns the k shortest path from src to dest
#sometimes it will return less than k shortest paths. This occurs when the max possible number of paths are less than k
k_shortest_yen <- function(graph, src, dest, k){
  if (src == dest) stop('src and dest can not be the same (currently)')

  #accepted paths
  A <- list(shortest_path(graph, src, dest))
  if (k == 1) return (A)
  #potential paths
  B <- list()

  for (k_i in 2:k){
    prev_path <- A[[k_i-1]]
    num_nodes_to_loop <- length(prev_path)-1
    for(i in 1:num_nodes_to_loop){
      spurNode <- prev_path[i]
      rootPath <- prev_path[1:i]

      edgesToDelete <- find_edges_to_delete(A, i,rootPath)
      t_g <- delete.edges(graph, edgesToDelete)
      #for (edge in edgesToDelete) t_g <- delete.edges(t_g, edge)

      spurPath <- shortest_path(t_g,spurNode, dest)

      if (!is.null(spurPath)){
        total_path <- list(c(rootPath[-i], spurPath))
        if (!total_path %in% B) B[length(B)+1] <- total_path
      }
    }
    if (length(B) == 0) break
    B <- sort_paths(graph, B)
    A[k_i] <- B[1]
    B <- B[-1]
    }
  A
}

#===================Test==========================#
edgeList <- tibble(from=character(), to=character(), weight = numeric())

edgeList[nrow(edgeList)+1,] <-list('c','d',3)
edgeList[nrow(edgeList)+1,] <-list('d','f',4)
edgeList[nrow(edgeList)+1,] <-list('f','h',1)
edgeList[nrow(edgeList)+1,] <-list('c','e',2)
edgeList[nrow(edgeList)+1,] <-list('e','d',1)
edgeList[nrow(edgeList)+1,] <-list('e','f',2)
edgeList[nrow(edgeList)+1,] <-list('e','g',3)
edgeList[nrow(edgeList)+1,] <-list('g','h',2)
edgeList[nrow(edgeList)+1,] <-list('f','g',2)

graph <- graph.data.frame(edgeList)

#k_shortest.yen(graph, 'c','c',7) #expect error
#expect all 7 paths 
k_shortest_yen(graph,'c','h',7)

【讨论】：

对我很有帮助。但是，是否可以计算出路径的权重值？？！我的意思是路径旅行时间。结果只显示遍历节点。谢谢！！

【解决方案2】：

我遇到了同样的问题，然后我注意到代码中有错误。函数 contains.path 中相同的函数没有返回正确的值。我只是将相同（x$variant$vert，variant）的代码更改为相同（unlist（x$variant$vert），unlist（variant））。现在代码正在报告所有路由，并且不存在重复。

【讨论】：

如何查看链接权重的总和？？！结果只显示了 [[1]]$g、[[1]]$path、[[1]]$vert 和 [[1]]$dist。 [[1]]$dist 仅显示节点数。我想将值乘以权重。！！谢谢