在Spark中将日期转换为月末

Question

我有一个Spark DataFrame,如下所示:

#Create DataFrame    
df <- data.frame(name = c("Thomas", "William", "Bill", "John"),
      dates = c('2017-01-05', '2017-02-23', '2017-03-16', '2017-04-08'))
df <- createDataFrame(df)

#Make sure df$dates column is in 'date' format    
df <- withColumn(df, 'dates', cast(df$dates, 'date'))

name    | dates
--------------------
Thomas  |2017-01-05
William |2017-02-23
Bill    |2017-03-16
John    |2017-04-08

我想更改dates为月末日期,因此它们看起来如下所示.我该怎么做呢？SparkR或PySpark代码都可以.

name    | dates
--------------------
Thomas  |2017-01-31
William |2017-02-28
Bill    |2017-03-31
John    |2017-04-30

Answer 1

您可以使用以下(PySpark):

from pyspark.sql.functions import last_day

df.select('name', last_day(df.dates).alias('dates')).show()

澄清last_day(date)一下,返回该日期所属月份的最后一天.

我很确定sparkR中有类似的功能 https://spark.apache.org/docs/1.6.2/api/R/last_day.html