如何从 Scala 方法创建 UDF(计算 md5)? [英] How to create UDF from Scala methods (to compute md5)?

问题描述

我想从两个已经运行的函数中构建一个 UDF.我正在尝试将 md5 哈希计算为现有 Spark 数据帧的新列.

I would like to build one UDF from two already working functions. I'm trying to calculate a md5 hash as a new column to an existing Spark Dataframe.

def md5(s: String): String = { toHex(MessageDigest.getInstance("MD5").digest(s.getBytes("UTF-8")))}
def toHex(bytes: Array[Byte]): String = bytes.map("%02x".format(_)).mkString("")

结构(我目前所拥有的)

val md5_hash: // UDF Implementation
val sqlfunc = udf(md5_hash)
val new_df = load_df.withColumn("New_MD5_Column", sqlfunc(col("Duration")))

不幸的是，我不知道如何将功能实现为 UDF.

Unfortunately i don't know how to propably implement the function as UDF.

推荐答案

您可以使用以下 udf 函数命名为 md5

you can use following udf function named as md5

import org.apache.spark.sql.functions._
def toHex(bytes: Array[Byte]): String = bytes.map("%02x".format(_)).mkString("")
def md5 = udf((s: String) => toHex(MessageDigest.getInstance("MD5").digest(s.getBytes("UTF-8"))))

val new_df = load_df.withColumn("New_MD5_Column", md5(col("Duration")))

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