我正在使用spark-sql-2.4.1v和java8。我需要计算一些给定数据的百分位数，比如25，75，90。
给定源数据集：

val df = Seq(
    (10, "1/15/2018", 0.010680705, 10, 0.619875458, 0.010680705, "east"),
    (10, "1/15/2018", 0.006628853,  4, 0.16039063, 0.01378215, "west"),
    (10, "1/15/2018", 0.01378215,  20, 0.082049528, 0.010680705, "east"),
    (10, "1/15/2018", 0.810680705,  6, 0.819875458, 0.702228853, "west"),
    (10, "1/15/2018", 0.702228853, 30, 0.916039063, 0.810680705, "east"),
    (11, "1/15/2018", 0.010680705, 10, 0.619875458, 0.010680705, "east"),
    (11, "1/15/2018", 0.006628853,  4, 0.16039063, 0.01378215,  "west"),
    (11, "1/15/2018", 0.01378215,  20, 0.082049528, 0.010680705, "east"),
    (11, "1/15/2018", 0.810680705,  6, 0.819875458, 0.702228853, "west"),
    (11, "1/15/2018", 0.702228853, 30, 0.916039063, 0.810680705,  "east"))  
  .toDF("id", "date", "revenue", "con_dist_1", "con_dist_2", "con_dist_3", "zone")

val percentiles = Seq(0.25, 0.75,0.90)  // Which percentiles to calculate
val cols = Seq("con_dist_1", "con_dist_2")  // The columns to use

+---+---------+-----------+----------+-----------+-----------+----+
| id|     date|    revenue|con_dist_1| con_dist_2| con_dist_3|zone|
+---+---------+-----------+----------+-----------+-----------+----+
| 10|1/15/2018|0.010680705|        10|0.619875458|0.010680705|east|
| 10|1/15/2018|0.006628853|         4| 0.16039063| 0.01378215|west|
| 10|1/15/2018| 0.01378215|        20|0.082049528|0.010680705|east|
| 10|1/15/2018|0.810680705|         6|0.819875458|0.702228853|west|
| 10|1/15/2018|0.702228853|        30|0.916039063|0.810680705|east|
| 11|1/15/2018|0.010680705|        10|0.619875458|0.010680705|east|
| 11|1/15/2018|0.006628853|         4| 0.16039063| 0.01378215|west|
| 11|1/15/2018| 0.01378215|        20|0.082049528|0.010680705|east|
| 11|1/15/2018|0.810680705|         6|0.819875458|0.702228853|west|
| 11|1/15/2018|0.702228853|        30|0.916039063|0.810680705|east|
+---+---------+-----------+----------+-----------+-----------+----+

我需要为给定的列计算每个区域的给定百分位数。如何做到这一点？
预期结果

+----+---------+-------------+-------------+------------+-------------+
|  id|     date|      revenue| perctile_col| quantile_0 |quantile_10  |
+----+---------+-------------+-------------+------------+-------------+
|  10|1/15/2018|  0.010680705| con_dist_1  |<quant0_val>|<quant10_val>|
|  10|1/15/2018|  0.010680705| con_dist_2  |<quant0_val>|<quant10_val>|
|  10|1/15/2018|  0.006628853| con_dist_1  |<quant0_val>|<quant10_val>|
|  10|1/15/2018|  0.006628853| con_dist_2  |<quant0_val>|<quant10_val>|
|  10|1/15/2018|   0.01378215| con_dist_1  |<quant0_val>|<quant10_val>|
|  10|1/15/2018|   0.01378215| con_dist_2  |<quant0_val>|<quant10_val>|
|  10|1/15/2018|  0.010680705| con_dist_1  |<quant0_val>|<quant10_val>|
|  10|1/15/2018|  0.010680705| con_dist_2  |<quant0_val>|<quant10_val>|
|  10|1/15/2018|  0.006628853| con_dist_1  |<quant0_val>|<quant10_val>|
|  10|1/15/2018|  0.006628853| con_dist_2  |<quant0_val>|<quant10_val>|
|  11|1/15/2018|  0.010680705| con_dist_1  |<quant0_val>|<quant10_val>|
|  11|1/15/2018|  0.010680705| con_dist_2  |<quant0_val>|<quant10_val>|
|  11|1/15/2018|  0.006628853| con_dist_1  |<quant0_val>|<quant10_val>|
|  11|1/15/2018|  0.006628853| con_dist_2  |<quant0_val>|<quant10_val>|
|  11|1/15/2018|   0.01378215| con_dist_1  |<quant0_val>|<quant10_val>|
|  11|1/15/2018|   0.01378215| con_dist_2  |<quant0_val>|<quant10_val>|
|  11|1/15/2018|  0.010680705| con_dist_1  |<quant0_val>|<quant10_val>|
|  11|1/15/2018|  0.010680705| con_dist_2  |<quant0_val>|<quant10_val>|
|  11|1/15/2018|  0.006628853| con_dist_1  |<quant0_val>|<quant10_val>|
|  11|1/15/2018|  0.006628853| con_dist_2  |<quant0_val>|<quant10_val>|
+----+---------+-------------+-------------+------------+-------------+

注：这里的分位数0等是百分位0、50等。