목록PySpark (14)

달나라 노트

Python pyspark : join, left join, right join, full outer join (spark dataframe join 하기)

pyspark dataframe도 여러 dataframe을 아래와 같은 4개의 join을 통해 합칠 수 있습니다. (inner) join left join right join full outer join join의 결과는 일반적인 sql에서의 join과 동일합니다. from pyspark.sql import SparkSession from pyspark.sql.functions import * import pandas as pd spark = SparkSession.builder.getOrCreate() df_item = pd.DataFrame({ 'id': [1, 2, 3], 'name': ['apple', 'banana', 'tomato'], 'price': [20000, 3500, 15000] })..
Python/Python pyspark 2021. 5. 31. 15:07
Python pyspark : drop (column 삭제하기)

Spark dataframe에 drop method를 적용하면 특정 column을 제거(drop)할 수 있습니다. from pyspark.sql import SparkSession from pyspark.sql.functions import col import pandas as pd spark = SparkSession.builder.getOrCreate() df_test = pd.DataFrame({ 'a': [1, 2, 3], 'b': [10.0, 3.5, 7.315], 'c': ['apple', 'banana', 'tomato'] }) df_spark = spark.createDataFrame(df_test) df_spark.show() df_spark_new = df_spark.drop(df_sp..
Python/Python pyspark 2021. 5. 31. 15:06
Python pyspark : lit (literal value로 column 만들기)

pyspark의 lit method는 literal value로 column을 생성할 때 사용됩니다. from pyspark.sql import SparkSession from pyspark.sql.functions import col, lit import pandas as pd spark = SparkSession.builder.getOrCreate() df_test = pd.DataFrame({ 'a': [1, 2, 3], 'b': [10.0, 3.5, 7.315], 'c': ['apple', 'banana', 'tomato'] }) df_spark = spark.createDataFrame(df_test) df_new = df_spark.select( col('a'), col('b'), lit('z..
Python/Python pyspark 2021. 5. 28. 20:24
Python pyspark : udf (사용자 정의 함수 User Defined Functions 사용하기)

udf method를 이용하면 만든 function을 column에 적용시킬 수 있습니다. from pyspark.sql import SparkSession from pyspark.sql.functions import udf from pyspark.sql.function import col import pandas as pd spark = SparkSession.builder.getOrCreate() df_test = pd.DataFrame({ 'a': [1, 2, 3], 'b': [10.0, 3.5, 7.315], 'c': ['apple', 'banana', 'tomato'] }) df_spark = spark.createDataFrame(df_test) def myfunc(x): # 1 return ..
Python/Python pyspark 2021. 5. 28. 20:13
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