pyspark - 在数据框中添加一列，其中包含从 1 到 n 的值

Question

我正在使用 pyspark 创建一个数据框，如下所示:

+----+------+
|   k|     v|
+----+------+
|key1|value1|
|key1|value1|
|key1|value1|
|key2|value1|
|key2|value1|
|key2|value1|
+----+------+

我想使用“withColumn”方法添加一个“rowNum”列，数据框的结果更改如下:

+----+------+------+
|   k|     v|rowNum|
+----+------+------+
|key1|value1|     1|
|key1|value1|     2|
|key1|value1|     3|
|key2|value1|     4|
|key2|value1|     5|
|key2|value1|     6|
+----+------+------+

rowNum的范围是从1到n，n等于raws的数量。我修改了我的代码，如下所示:

from pyspark.sql.window import Window
from pyspark.sql import functions as F
w = Window().partitionBy("v").orderBy('k')
my_df= my_df.withColumn("rowNum", F.rowNumber().over(w))

但是，我收到错误消息:

'module' object has no attribute 'rowNumber' 

我将rowNumber()方法替换为row_number，上面的代码可以运行。但是，当我运行代码时:

my_df.show()

我再次收到错误消息:

Py4JJavaError: An error occurred while calling o898.showString.
: java.lang.UnsupportedOperationException: Cannot evaluate expression: row_number()
    at org.apache.spark.sql.catalyst.expressions.Unevaluable$class.doGenCode(Expression.scala:224)
    at org.apache.spark.sql.catalyst.expressions.aggregate.DeclarativeAggregate.doGenCode(interfaces.scala:342)
    at org.apache.spark.sql.catalyst.expressions.Expression$$anonfun$genCode$2.apply(Expression.scala:104)
    at org.apache.spark.sql.catalyst.expressions.Expression$$anonfun$genCode$2.apply(Expression.scala:101)
    at scala.Option.getOrElse(Option.scala:121)

Answer 1

Spark 2.2中的解决方案:

from pyspark.sql.functions import row_number,lit
from pyspark.sql.window import Window
w = Window().orderBy(lit('A'))
df = df.withColumn("rowNum", row_number().over(w))