R 将一个大数据帧拆分为多个数据块，但确保具有相同列值的行最终位于同一数据块中

我需要使用几个函数，这些函数对于多达1000行的数据帧非常有效，但对于更大的数据集来说，这是不可能的

我需要分析的df有93645行。它的外观示例如下：

    Locus.ID Chr  BP Col Pop.ID
125       88  un 620  38      8
126       88  un 620  38      9
127       92  un 701  36      1
128       92  un 701  36      2
129       92  un 701  36      3
130       92  un 701  36      4
131       92  un 701  36      5
132       92  un 701  36      6
133       92  un 701  36      7
134       92  un 701  36      8
135       92  un 701  36      9
136      115  un 859  28      1
137      115  un 859  28      2

没有必要一次分析所有的数据，所以我想把它分成1000组。但是，只有一个条件：我不应该在不同的块中有列

Locus.ID

具有相同值的行，如果是这样的话，那么我就不能对每个块单独应用下游分析

真正的数据集有5874个不同级别的

Locus.ID

。它们可以出现在一行或多行中，但不以任何特定模式出现

如何将数据帧分割为约1000行的块，以确保具有相同值

Locus.ID

的行最终位于同一块中

非常感谢你的帮助，我希望我没有遗漏一些明显的东西

下面是500行df子集的dput

df<-structure(list(Locus.ID = c(2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L,  2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L,  2L, 2L, 9L, 9L, 9L, 9L, 9L, 9L, 9L, 9L, 9L, 9L, 9L, 9L, 9L, 9L,  9L, 9L, 9L, 9L, 16L, 16L, 16L, 16L, 16L, 16L, 16L, 16L, 16L,  16L, 16L, 16L, 16L, 16L, 16L, 16L, 16L, 16L, 69L, 69L, 69L, 69L,  69L, 69L, 69L, 69L, 69L, 69L, 69L, 69L, 69L, 69L, 69L, 69L, 69L,  69L, 74L, 74L, 74L, 74L, 74L, 74L, 74L, 74L, 74L, 77L, 77L, 77L,  77L, 77L, 77L, 77L, 77L, 77L, 80L, 80L, 80L, 80L, 80L, 80L, 80L,  80L, 80L, 88L, 88L, 88L, 88L, 88L, 88L, 88L, 88L, 88L, 88L, 88L,  88L, 88L, 88L, 88L, 88L, 88L, 88L, 92L, 92L, 92L, 92L, 92L, 92L,  92L, 92L, 92L, 115L, 115L, 115L, 115L, 115L, 115L, 115L, 115L,  115L, 115L, 115L, 115L, 115L, 115L, 115L, 115L, 115L, 115L, 119L,  119L, 119L, 119L, 119L, 119L, 119L, 119L, 125L, 125L, 125L, 125L,  125L, 125L, 125L, 125L, 125L, 125L, 125L, 125L, 125L, 125L, 125L,  125L, 125L, 125L, 131L, 131L, 131L, 131L, 131L, 131L, 131L, 131L,  131L, 131L, 131L, 131L, 131L, 131L, 131L, 131L, 131L, 131L, 136L,  136L, 136L, 136L, 136L, 136L, 136L, 136L, 136L, 136L, 136L, 136L,  136L, 136L, 136L, 136L, 136L, 136L, 139L, 139L, 139L, 139L, 139L,  139L, 139L, 139L, 139L, 139L, 139L, 139L, 139L, 139L, 139L, 139L,  139L, 139L, 139L, 139L, 139L, 139L, 139L, 139L, 139L, 139L, 139L,  160L, 160L, 160L, 160L, 160L, 160L, 160L, 160L, 160L, 160L, 160L,  160L, 160L, 160L, 160L, 160L, 160L, 160L, 164L, 164L, 164L, 164L,  164L, 164L, 164L, 164L, 164L, 166L, 166L, 166L, 166L, 166L, 166L,  166L, 166L, 166L, 170L, 170L, 170L, 170L, 170L, 170L, 170L, 170L,  170L, 170L, 170L, 170L, 170L, 170L, 170L, 170L, 170L, 170L, 170L,  170L, 170L, 170L, 170L, 170L, 170L, 170L, 170L, 187L, 187L, 187L,  187L, 187L, 187L, 187L, 187L, 187L, 192L, 192L, 192L, 192L, 192L,  192L, 192L, 192L, 192L, 206L, 206L, 206L, 206L, 206L, 206L, 206L,  206L, 206L, 233L, 233L, 233L, 233L, 233L, 233L, 233L, 233L, 233L,  233L, 233L, 233L, 233L, 233L, 233L, 233L, 233L, 233L, 249L, 249L,  249L, 249L, 249L, 249L, 249L, 249L, 249L, 257L, 257L, 257L, 257L,  257L, 257L, 257L, 257L, 257L, 257L, 257L, 257L, 257L, 257L, 257L,  257L, 257L, 257L, 257L, 257L, 257L, 257L, 257L, 257L, 257L, 257L,  257L, 262L, 262L, 262L, 262L, 262L, 262L, 262L, 262L, 262L, 291L,  291L, 291L, 291L, 291L, 291L, 291L, 291L, 291L, 291L, 291L, 291L,  291L, 291L, 291L, 291L, 291L, 291L, 294L, 294L, 294L, 294L, 294L,  294L, 294L, 294L, 294L, 319L, 319L, 319L, 319L, 319L, 319L, 319L,  319L, 319L, 319L, 319L, 319L, 319L, 319L, 319L, 319L, 319L, 319L,  319L, 319L, 319L, 319L, 319L, 319L, 319L, 319L, 319L, 319L, 319L,  319L, 319L, 319L, 319L, 319L, 319L, 319L, 377L, 377L, 377L, 377L,  377L, 377L, 377L, 377L, 377L, 377L, 377L, 377L, 377L, 377L, 377L,  377L, 377L, 377L, 377L, 377L, 377L, 377L, 377L, 377L, 377L, 377L,  377L, 387L, 387L, 387L, 387L, 387L, 387L, 387L, 387L, 387L, 416L,  416L, 416L, 416L, 416L, 416L), Chr = structure(c(1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,  1L), .Label = "un", class = "factor"), BP = c(10L, 10L, 10L,  10L, 10L, 10L, 10L, 10L, 10L, 54L, 54L, 54L, 54L, 54L, 54L, 54L,  54L, 54L, 55L, 55L, 55L, 55L, 55L, 55L, 55L, 55L, 55L, 99L, 99L,  99L, 99L, 99L, 99L, 99L, 99L, 99L, 125L, 125L, 125L, 125L, 125L,  125L, 125L, 125L, 125L, 172L, 172L, 172L, 172L, 172L, 172L, 180L,  180L, 180L, 180L, 180L, 180L, 211L, 211L, 211L, 211L, 211L, 211L,  269L, 269L, 269L, 269L, 269L, 269L, 269L, 269L, 269L, 307L, 307L,  307L, 307L, 307L, 307L, 307L, 307L, 307L, 368L, 368L, 368L, 368L,  368L, 368L, 368L, 368L, 368L, 465L, 465L, 465L, 465L, 465L, 465L,  465L, 465L, 465L, 516L, 516L, 516L, 516L, 516L, 516L, 516L, 516L,  516L, 587L, 587L, 587L, 587L, 587L, 587L, 587L, 587L, 587L, 620L,  620L, 620L, 620L, 620L, 620L, 620L, 620L, 620L, 701L, 701L, 701L,  701L, 701L, 701L, 701L, 701L, 701L, 859L, 859L, 859L, 859L, 859L,  859L, 859L, 859L, 859L, 886L, 886L, 886L, 886L, 886L, 886L, 886L,  886L, 886L, 975L, 975L, 975L, 975L, 975L, 975L, 975L, 975L, 1027L,  1027L, 1027L, 1027L, 1027L, 1027L, 1027L, 1027L, 1027L, 1034L,  1034L, 1034L, 1034L, 1034L, 1034L, 1034L, 1034L, 1034L, 1086L,  1086L, 1086L, 1086L, 1086L, 1086L, 1086L, 1086L, 1086L, 1115L,  1115L, 1115L, 1115L, 1115L, 1115L, 1115L, 1115L, 1115L, 1232L, 1232L, 1232L, 1232L, 1232L, 1232L, 1232L, 1232L, 1232L, 1236L,  1236L, 1236L, 1236L, 1236L, 1236L, 1236L, 1236L, 1236L, 1273L,  1273L, 1273L, 1273L, 1273L, 1273L, 1273L, 1273L, 1273L, 1311L,  1311L, 1311L, 1311L, 1311L, 1311L, 1311L, 1311L, 1311L, 1312L,  1312L, 1312L, 1312L, 1312L, 1312L, 1312L, 1312L, 1312L, 1440L,  1440L, 1440L, 1440L, 1440L, 1440L, 1440L, 1440L, 1440L, 1451L,  1451L, 1451L, 1451L, 1451L, 1451L, 1451L, 1451L, 1451L, 1500L,  1500L, 1500L, 1500L, 1500L, 1500L, 1500L, 1500L, 1500L, 1629L,  1629L, 1629L, 1629L, 1629L, 1629L, 1629L, 1629L, 1629L, 1682L,  1682L, 1682L, 1682L, 1682L, 1682L, 1682L, 1682L, 1682L, 1702L, 1702L, 1702L, 1702L, 1702L, 1702L, 1702L, 1702L, 1702L, 1707L,  1707L, 1707L, 1707L, 1707L, 1707L, 1707L, 1707L, 1707L, 1793L,  1793L, 1793L, 1793L, 1793L, 1793L, 1793L, 1793L, 1793L, 1866L,  1866L, 1866L, 1866L, 1866L, 1866L, 1866L, 1866L, 1866L, 1917L,  1917L, 1917L, 1917L, 1917L, 1917L, 1917L, 1917L, 1917L, 2046L,  2046L, 2046L, 2046L, 2046L, 2046L, 2046L, 2046L, 2046L, 2059L,  2059L, 2059L, 2059L, 2059L, 2059L, 2059L, 2059L, 2059L, 2099L,  2099L, 2099L, 2099L, 2099L, 2099L, 2099L, 2099L, 2099L, 2177L,  2177L, 2177L, 2177L, 2177L, 2177L, 2177L, 2177L, 2177L, 2178L,  2178L, 2178L, 2178L, 2178L, 2178L, 2178L, 2178L, 2178L, 2190L, 2190L, 2190L, 2190L, 2190L, 2190L, 2190L, 2190L, 2190L, 2255L,  2255L, 2255L, 2255L, 2255L, 2255L, 2255L, 2255L, 2255L, 2344L,  2344L, 2344L, 2344L, 2344L, 2344L, 2344L, 2344L, 2344L, 2381L,  2381L, 2381L, 2381L, 2381L, 2381L, 2381L, 2381L, 2381L, 2423L,  2423L, 2423L, 2423L, 2423L, 2423L, 2423L, 2423L, 2423L, 2590L,  2590L, 2590L, 2590L, 2590L, 2590L, 2590L, 2590L, 2590L, 2596L,  2596L, 2596L, 2596L, 2596L, 2596L, 2596L, 2596L, 2596L, 2597L,  2597L, 2597L, 2597L, 2597L, 2597L, 2597L, 2597L, 2597L, 2611L,  2611L, 2611L, 2611L, 2611L, 2611L, 2611L, 2611L, 2611L, 2662L,  2662L, 2662L, 2662L, 2662L, 2662L, 2662L, 2662L, 2662L, 2676L, 2676L, 2676L, 2676L, 2676L, 2676L, 2676L, 2676L, 2676L, 2680L,  2680L, 2680L, 2680L, 2680L, 2680L, 2680L, 2680L, 2680L, 2792L,  2792L, 2792L, 2792L, 2792L, 2792L, 2792L, 2792L, 2792L, 2830L,  2830L, 2830L, 2830L, 2830L, 2830L), Col = c(9L, 9L, 9L, 9L, 9L,  9L, 9L, 9L, 9L, 53L, 53L, 53L, 53L, 53L, 53L, 53L, 53L, 53L,  54L, 54L, 54L, 54L, 54L, 54L, 54L, 54L, 54L, 15L, 15L, 15L, 15L,  15L, 15L, 15L, 15L, 15L, 41L, 41L, 41L, 41L, 41L, 41L, 41L, 41L,  41L, 5L, 5L, 5L, 5L, 5L, 5L, 13L, 13L, 13L, 13L, 13L, 13L, 44L,  44L, 44L, 44L, 44L, 44L, 19L, 19L, 19L, 19L, 19L, 19L, 19L, 19L,  19L, 57L, 57L, 57L, 57L, 57L, 57L, 57L, 57L, 57L, 35L, 35L, 35L,  35L, 35L, 35L, 35L, 35L, 35L, 49L, 49L, 49L, 49L, 49L, 49L, 49L,  49L, 49L, 17L, 17L, 17L, 17L, 17L, 17L, 17L, 17L, 17L, 5L, 5L,  5L, 5L, 5L, 5L, 5L, 5L, 5L, 38L, 38L, 38L, 38L, 38L, 38L, 38L,  38L, 38L, 36L, 36L, 36L, 36L, 36L, 36L, 36L, 36L, 36L, 28L, 28L,  28L, 28L, 28L, 28L, 28L, 28L, 28L, 55L, 55L, 55L, 55L, 55L, 55L,  55L, 55L, 55L, 61L, 61L, 61L, 61L, 61L, 61L, 61L, 61L, 30L, 30L,  30L, 30L, 30L, 30L, 30L, 30L, 30L, 37L, 37L, 37L, 37L, 37L, 37L,  37L, 37L, 37L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 35L, 35L,  35L, 35L, 35L, 35L, 35L, 35L, 35L, 69L, 69L, 69L, 69L, 69L, 69L,  69L, 69L, 69L, 73L, 73L, 73L, 73L, 73L, 73L, 73L, 73L, 73L, 27L,  27L, 27L, 27L, 27L, 27L, 27L, 27L, 27L, 65L, 65L, 65L, 65L, 65L,  65L, 65L, 65L, 65L, 66L, 66L, 66L, 66L, 66L, 66L, 66L, 66L, 66L,  28L, 28L, 28L, 28L, 28L, 28L, 28L, 28L, 28L, 39L, 39L, 39L, 39L,  39L, 39L, 39L, 39L, 39L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L,  51L, 51L, 51L, 51L, 51L, 51L, 51L, 51L, 51L, 21L, 21L, 21L, 21L,  21L, 21L, 21L, 21L, 21L, 41L, 41L, 41L, 41L, 41L, 41L, 41L, 41L, 41L, 46L, 46L, 46L, 46L, 46L, 46L, 46L, 46L, 46L, 49L, 49L, 49L,  49L, 49L, 49L, 49L, 49L, 49L, 39L, 39L, 39L, 39L, 39L, 39L, 39L,  39L, 39L, 7L, 7L, 7L, 7L, 7L, 7L, 7L, 7L, 7L, 53L, 53L, 53L,  53L, 53L, 53L, 53L, 53L, 53L, 66L, 66L, 66L, 66L, 66L, 66L, 66L,  66L, 66L, 23L, 23L, 23L, 23L, 23L, 23L, 23L, 23L, 23L, 18L, 18L,  18L, 18L, 18L, 18L, 18L, 18L, 18L, 19L, 19L, 19L, 19L, 19L, 19L,  19L, 19L, 19L, 31L, 31L, 31L, 31L, 31L, 31L, 31L, 31L, 31L, 13L,  13L, 13L, 13L, 13L, 13L, 13L, 13L, 13L, 19L, 19L, 19L, 19L, 19L,  19L, 19L, 19L, 19L, 56L, 56L, 56L, 56L, 56L, 56L, 56L, 56L, 56L,  15L, 15L, 15L, 15L, 15L, 15L, 15L, 15L, 15L, 16L, 16L, 16L, 16L,  16L, 16L, 16L, 16L, 16L, 22L, 22L, 22L, 22L, 22L, 22L, 22L, 22L,  22L, 23L, 23L, 23L, 23L, 23L, 23L, 23L, 23L, 23L, 37L, 37L, 37L,  37L, 37L, 37L, 37L, 37L, 37L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L,  5L, 19L, 19L, 19L, 19L, 19L, 19L, 19L, 19L, 19L, 23L, 23L, 23L,  23L, 23L, 23L, 23L, 23L, 23L, 52L, 52L, 52L, 52L, 52L, 52L, 52L,  52L, 52L, 7L, 7L, 7L, 7L, 7L, 7L), Pop.ID = c(1L, 2L, 3L, 4L,  5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L,  3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L,  1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 2L, 3L, 4L, 6L, 7L, 8L, 2L,  3L, 4L, 6L, 7L, 8L, 2L, 3L, 4L, 6L, 7L, 8L, 1L, 2L, 3L, 4L, 5L,  6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L,  4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L,  2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L,  9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L,  7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L,  5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 1L, 2L, 3L,  4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L,  2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L,  9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L,  7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L,  5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L,  3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L,  1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L,  8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L,  6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L,  4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L,  2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L,  9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L,  7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L,  5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L,  3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L,  1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L,  8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L,  6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L,  4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L,  2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L,  9L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 1L, 2L, 3L, 4L, 5L, 6L )), .Names = c("Locus.ID", "Chr", "BP", "Col", "Pop.ID"), class = "data.frame", row.names = c(NA,  500L))

---

df这样可以拆分数据帧。之后，为了简单起见，您可以将不同的部分切割成所需的大小S（这里我假设为1）

> S <- 1

> df <- data.frame(a=c(1,1,2,2,3,3),b=1:6)
> df
  a b
1 1 1
2 1 2
3 2 3
4 2 4
5 3 5
6 3 6

> dfs <- split(df,df$a)
> dfs
$`1`
  a b
1 1 1
2 1 2

$`2`
  a b
3 2 3
4 2 4

$`3`
  a b
5 3 5
6 3 6

> lapply(dfs,function(df) df[1:min(S,nrow(df)),])
$`1`
  a b
1 1 1

$`2`
  a b
3 2 3

$`3`
  a b
5 3 5

>S df
a b
1 1 1
2 1 2
3 2 3
4 2 4
5 3 5
6 3 6
>dfs
$`1`
a b
1 1 1
2 1 2
$`2`
a b
3 2 3
4 2 4
$`3`
a b
5 3 5
6 3 6
>lapply（dfs，功能（df）df[1:min（S，nrow（df）），]
$`1`
a b
1 1 1
$`2`
a b
3 2 3
$`3`
a b
5 3 5