类型转换 (TypeConvertStreamOp)

Java 类名：com.alibaba.alink.operator.stream.dataproc.TypeConvertStreamOp

Python 类名：TypeConvertStreamOp

功能介绍

类型转换是用来列类型进行转换的组件。本组件可一次性转化多个列到指定的数据类型，但是这些列的数据类型只能为同一种，并且为JDBC Type。

组件支持的目标类型为 STRING, VARCHAR, FLOAT, DOUBLE, INT, BIGINT, LONG, BOOLEAN。

参数说明

名称	中文名称	描述	类型	是否必须？	取值范围	默认值
targetType	目标类型	转换为的类型，类型应该为JDBC Type。	String	✓	“STRING”, “VARCHAR”, “FLOAT”, “DOUBLE”, “INT”, “BIGINT”, “LONG”, “BOOLEAN”, “DECIMAL”
selectedCols	选中的列名数组	计算列对应的列名列表	String[]			null

代码示例

Python 代码

from pyalink.alink import *

import pandas as pd

useLocalEnv(1)

df_data = pd.DataFrame([
    ['Ohio', 2000, 1.5],
    ['Ohio', 2001, 1.7],
    ['Ohio', 2002, 3.6],
    ['Nevada', 2001, 2.4],
    ['Nevada', 2002, 2.9],
    ['Nevada', 2003,3.2]
])

stream_data = StreamOperator.fromDataframe(df_data, schemaStr='f1 string, f2 bigint, f3 double')

op = TypeConvertStreamOp()\
        .setSelectedCols(['f2'])\
        .setTargetType('double')

stream_data.link(op).print()

StreamOperator.execute()

Java 代码

import org.apache.flink.types.Row;

import com.alibaba.alink.operator.stream.StreamOperator;
import com.alibaba.alink.operator.stream.source.MemSourceStreamOp;
import com.alibaba.alink.operator.stream.dataproc.TypeConvertStreamOp;
import org.junit.Test;

import java.util.Arrays;
import java.util.List;

public class TypeConvertStreamOpTest {
	@Test
	public void testTypeConvertStreamOp() throws Exception {
		List <Row> inputData = Arrays.asList(
			Row.of("Ohio", 2000L, 1.5),
			Row.of("Ohio", 2001L, 1.7),
			Row.of("Ohio", 2002L, 3.6),
			Row.of("Nevada", 2001L, 2.4),
			Row.of("Nevada", 2002L, 2.9),
			Row.of("Nevada", 2003L,3.2)
		);
		StreamOperator<?> memSourceStreamOp = new MemSourceStreamOp(inputData, "f1 string, f2 bigint, f3 double");
		new TypeConvertStreamOp()
			.setSelectedCols("f2")
			.setTargetType("double")
			.linkFrom(memSourceStreamOp)
			.print();

		StreamOperator.execute();
	}
}

运行结果

f1 |f2 |f3 
---|---|---
Ohio|2000.0000|1.5000
Ohio|2001.0000|1.7000
Ohio|2002.0000|3.6000
Nevada|2001.0000|2.4000
Nevada|2002.0000|2.9000
Nevada|2003.0000|3.2000