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May 11, 2021 23:11
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pyspark UDF
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import pyspark | |
from pyspark.sql import SparkSession | |
from pyspark.sql.functions import col, udf | |
from pyspark.sql.types import StringType | |
spark = SparkSession.builder.appName('SparkByExamples.com').getOrCreate() | |
columns = ["Seqno","Name"] | |
data = [("1", "john jones"), | |
("2", "tracey smith"), | |
("3", "amy sanders")] | |
df = spark.createDataFrame(data=data,schema=columns) | |
df.show(truncate=False) | |
def convertCase(str): | |
resStr="" | |
arr = str.split(" ") | |
for x in arr: | |
resStr= resStr + x[0:1].upper() + x[1:len(x)] + " " | |
return resStr | |
""" Converting function to UDF """ | |
convertUDF = udf(lambda z: convertCase(z)) | |
df.select(col("Seqno"), \ | |
convertUDF(col("Name")).alias("Name") ) \ | |
.show(truncate=False) | |
def upperCase(str): | |
return str.upper() | |
upperCaseUDF = udf(lambda z:upperCase(z),StringType()) | |
df.withColumn("Cureated Name", upperCaseUDF(col("Name"))) \ | |
.show(truncate=False) | |
""" Using UDF on SQL """ | |
spark.udf.register("convertUDF", convertCase,StringType()) | |
df.createOrReplaceTempView("NAME_TABLE") | |
spark.sql("select Seqno, convertUDF(Name) as Name from NAME_TABLE") \ | |
.show(truncate=False) | |
spark.sql("select Seqno, convertUDF(Name) as Name from NAME_TABLE " + \ | |
"where Name is not null and convertUDF(Name) like '%John%'") \ | |
.show(truncate=False) | |
""" null check """ | |
columns = ["Seqno","Name"] | |
data = [("1", "john jones"), | |
("2", "tracey smith"), | |
("3", "amy sanders"), | |
('4',None)] | |
df2 = spark.createDataFrame(data=data,schema=columns) | |
df2.show(truncate=False) | |
df2.createOrReplaceTempView("NAME_TABLE2") | |
spark.udf.register("_nullsafeUDF", lambda str: convertCase(str) if not str is None else "" , StringType()) | |
spark.sql("select _nullsafeUDF(Name) from NAME_TABLE2") \ | |
.show(truncate=False) | |
spark.sql("select Seqno, _nullsafeUDF(Name) as Name from NAME_TABLE2 " + \ | |
" where Name is not null and _nullsafeUDF(Name) like '%John%'") \ | |
.show(truncate=False) |
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