SparkSql学习---单词词频统计案例_使用spark sql实现单词统计

数据源：words.txt

hello spark
hello hadoop
hello flink

代码：

# coding:utf8
 
from pyspark.sql import SparkSession
from pyspark.sql.types import StructType, StringType, IntegerType
import pandas as pd
from pyspark.sql import functions as F
 
 
if __name__ == '__main__':
    # 0. 构建执行环境入口对象SparkSession
    spark = SparkSession.builder.appName("test").master("local[*]").getOrCreate()
    sc = spark.sparkContext
 
    # TODO 1: SQL 风格进行处理
    rdd = sc.textFile("../data/input/words.txt").flatMap(lambda x: x.split(" ")).map(lambda x: [x])
    print(rdd.collect())
    df = rdd.toDF(["word"])
 
    # 注册DF为表格
    df.createTempView("words")
 
    spark.sql("SELECT word, COUNT(*) AS cnt FROM words GROUP BY word ORDER BY cnt DESC").show()
 
 
    # TODO 2: DSL 风格处理
    df = spark.read.format("text").load("../data/input/words.txt")
 
    # withColumn方法
    # 方法功能: 对已存在的列进行操作, 返回一个新的列, 如果名字和老列相同, 那么替换, 否则作为新列存在
    df2 = df.withColumn("value", F.explode(F.split(df['value'], " ")))
    df2.groupBy("value").count().withColumnRenamed("value", "word").withColumnRenamed("count", "cnt").\
        orderBy("cnt", ascending=False).show()

运行结果：