By using withColumn(), sql(), select() you can apply a built-in function or custom function to a column. In order to apply a custom function, first you need to create a function and register the function as a UDF. Recent versions of PySpark provide a way to use Pandas API hence, y...
textCol: org.apache.spark.sql.Column=text scala> val textCol = dataset.apply("text") textCol: org.apache.spark.sql.Column=text scala> val textCol = dataset("text") textCol: org.apache.spark.sql.Column= text
spark Column 原理用法示例源码分析 一、原理 Spark 的 Column 类是Spark SQL 中用于表示列操作和表达式的核心类之一。它是一个不可变类,封装了对数据集中某一列的操作和转换。 Column 的实现原理主要依赖于 Spark SQL 的逻辑优化器和物理执行引擎。下面是 Column 类的几个关键特点和原理: 表达式树:Column 实际上...
Column to apply offset Int32 Offset from the current row defaultValue Object Default value when the offset row doesn't exist Returns Column Column object Remarks This is equivalent to the LEAD function in SQL. Applies to Microsoft.Spark latest ...
// 定义一个自定义函数,将某一列的值转换为大写 UserDefinedFunction toUpperCase = functions.udf( (String value) -> value.toUpperCase(), DataTypes.StringType); 使用withColumn函数添加或替换列: 代码语言:txt 复制 // 添加一个新列,将原始列的值转换为大写 df = df.withColumn("newColumn", toUpperCase....
gapply 將函式套用至 的每個群組SparkDataFrame。 函式會套用至 的每個群組,SparkDataFrame而且應該只有兩個參數:將索引鍵和 Rdata.frame分組至該索引鍵。 群組是從 columnSparkDataFrames(s) 中選擇的。 函式的輸出應該是data.frame。 架構會指定所產生SparkDataFrame的數據列格式。 它必須代表來自 Spark資料類型的...
Window function: returns the value that is 'offset' rows after the current row, and null if there is less than 'offset' rows after the current row. For example, an 'offset' of one will return the next row at any given point in the window partition.
This is equivalent to the LEAD function in SQL. Applies to Microsoft.Spark latest ProductVersies Microsoft.Sparklatest Lead(Column, Int32, Object) Window function: returns the value that is 'offset' rows after the current row, and null if there is less than 'offset' rows after the current...
Column to apply offset Int32 Offset from the current row defaultValue Object Default value when the offset row doesn't exist Returns Column Column object Remarks This is equivalent to the LEAD function in SQL. Applies to Microsoft.Spark latest ...
Window function: returns the value that is 'offset' rows after the current row, and null if there is less than 'offset' rows after the current row. For example, an 'offset' of one will return the next row at any given point in the window partition.