Pyspark 创建一个包含计算值的汇总表

Question

我有一个如下所示的数据框：

+--------------------+---------------------+-------------+------------+-----+
|tpep_pickup_datetime|tpep_dropoff_datetime|trip_distance|total_amount|isDay|
+--------------------+---------------------+-------------+------------+-----+
| 2019-01-01 09:01:00|  2019-01-01 08:53:20|          1.5|        2.00| true|
| 2019-01-01 21:59:59|  2019-01-01 21:18:59|          2.6|        5.00|false|
| 2019-01-01 10:01:00|  2019-01-01 08:53:20|          1.5|        2.00| true|
| 2019-01-01 22:59:59|  2019-01-01 21:18:59|          2.6|        5.00|false|
+--------------------+---------------------+-------------+------------+-----+

我想创建一个汇总表，计算所有夜间旅行和所有白天旅行的trip_rate（total_amount 列除以trip_distance）。所以最终结果应该是这样的：

+------------+-----------+
| day_night  | trip_rate |
+------------+-----------+
|Day         | 1.33      |
|Night       | 1.92      |
+------------+-----------+

这是我想要做的：

df2 = spark.createDataFrame(
    [
        ('2019-01-01 09:01:00','2019-01-01 08:53:20','1.5','2.00','true'),#day
        ('2019-01-01 21:59:59','2019-01-01 21:18:59','2.6','5.00','false'),#night
        ('2019-01-01 10:01:00','2019-01-01 08:53:20','1.5','2.00','true'),#day
        ('2019-01-01 22:59:59','2019-01-01 21:18:59','2.6','5.00','false'),#night
    ],
    ['tpep_pickup_datetime','tpep_dropoff_datetime','trip_distance','total_amount','day_night'] # add your columns label here
)

day_trip_rate = df2.where(df2.day_night == 'Day').withColumn("trip_rate",F.sum("total_amount")/F.sum("trip_distance"))
night_trip_rate = df2.where(df2.day_night == 'Night').withColumn("trip_rate",F.sum("total_amount")/F.sum("trip_distance"))

我什至不相信我以正确的方式接近它。我收到了这个错误:( raise AnalysisException(s.split(': ', 1)[1], stackTrace) pyspark.sql.utils.AnalysisException: "grouping expressions sequence is empty, and 'tpep_pickup_datetime' is not an aggregate function.

有人可以帮我知道如何处理这个来获得那个汇总表吗？

Answer 1

from pyspark.sql import functions as F
from pyspark.sql.functions import *

df2.groupBy("day_night").agg(F.round(F.sum("total_amount")/F.sum("trip_distance"),2).alias('trip_rate'))\
        .withColumn("day_night", F.when(col("day_night")=="true", "Day").otherwise("Night")).show()

+---------+---------+
|day_night|trip_rate|
+---------+---------+
|      Day|     1.33|
|    Night|     1.92|
+---------+---------+

不四舍五入：

df2.groupBy("day_night").agg(F.sum("total_amount")/F.sum("trip_distance")).alias('trip_rate')\
        .withColumn("day_night", F.when(col("day_night")=="true", "Day").otherwise("Night")).show()

（你在df2构造代码中有day_night，但在显示表中有isDay。我在这里考虑字段名称为day_night。）