values:选中的列(LIST)variableColumnName: 列名valueColumnName:对应列的值宽表转长表,一行变多行,除了选中的ids是不变的,但是会把选中的values中的列由列变成行记录,variableColumnName记录了反转前的列名,valueColumnName 对应 variableColumnName 存储值。 data.show()+
* Pivots a column of the current `DataFrame` and performs the specified aggregation. * There are two versions of pivot function: one that requires the caller to specify the list * of distinct values to pivot on, and one that does not. The latter is more concise but less * efficient, be...
添加列是很重要的一个操作，在 PQ 的查询编辑器界面，有一个专门【添加列】功能区。在讲解添加列的过...
# if you have headers in your csv file: headers = list(pd.read_csv("Your_Data_File.csv", nrows=0).columns) for chunky in chunk_100k: Spark_Full += sc.parallelize(chunky.values.tolist()) YourSparkDataFrame = Spark_Full.toDF(headers) # if you do not have headers, leave empty inste...
()进行数据聚合操作:from pyspark.sql import SparkSessionfrom pyspark.sql.functions...读取 CSV 文件并创建 DataFramedf = spark.read.csv("path/to/your/file.csv", header=True, inferSchema=True)# 按某一列进行分组...按某一列进行分组:使用 groupBy("column_name1") 方法按 column_name1 列对数据...
--Returning a Column that contains <value> in every row: F.lit(<value>) -- Example df = df.withColumn("test",F.lit(1)) -- Example for null values: you have to give a type to the column since None has no type df = df.withColumn("null_column",F.lit(None).cast("string")) ...
示例二 from pyspark.sql import Row from pyspark.sql.functions import explode eDF = spark.createDataFrame([Row( a=1, intlist=[1, 2, 3], mapfield={"a": "b"})]) eDF.select(explode(eDF.intlist).alias("anInt")).show() +---+ |anInt| +---+ | 1| | 2| | 3| +---+ isin...
if key != 'some_column_name': value = dict_row[key] if value is None: value_in = str("") else: value_in = str(value) dict_row[key] = value_in columns = dict_row.keys() v = dict_row.values() row = Row(*columns)
df.toPandas() 2.选择和访问数据 PySpark DataFrame是惰性求值的,只是选择一列并不会触发计算,而是返回一个Column实例。 df.a 事实上,大多数按列操作都会返回Column实例。 from pyspark.sql import Column from pyspark.sql.functions import upper type(df.c) == type(upper(df.c)) == type(df.c.isNull(...
dataList = sparkSession.sparkContext.parallelize([(1, "Katie", 19),(2,"Tom",20)]) schema = StructType([StructField("id", IntegerType(), False), StructField("name", StringType(), False), StructField("age", IntegerType(), False)]) dataFrame = sparkSession.createDataFrame(dataList, ...