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請在下面找到代碼並讓我知道如何將列名更改爲小寫。我嘗試過使用ColumnRename,但是我必須爲每列執行並輸入所有列名稱。我只是想在列上做,所以我不想提及所有列名稱,因爲它們有太多。Spark Scala CSV列名爲小寫
斯卡拉版本:2.11 星火:2.2
import org.apache.spark.sql.SparkSession
import org.apache.log4j.{Level, Logger}
import com.datastax
import org.apache.spark.SparkContext
import org.apache.spark.SparkConf
import com.datastax.spark.connector._
import org.apache.spark.sql._
object dataframeset {
def main(args: Array[String]): Unit = {
val conf = new SparkConf().setAppName("Sample1").setMaster("local[*]")
val sc = new SparkContext(conf)
sc.setLogLevel("ERROR")
val rdd1 = sc.cassandraTable("tdata", "map3")
Logger.getLogger("org").setLevel(Level.ERROR)
Logger.getLogger("akka").setLevel(Level.ERROR)
val spark1 = org.apache.spark.sql.SparkSession.builder().master("local").config("spark.cassandra.connection.host","127.0.0.1")
.appName("Spark SQL basic example").getOrCreate()
val df = spark1.read.format("csv").option("header","true").option("inferschema", "true").load("/Users/Desktop/del2.csv")
import spark1.implicits._
println("\nTop Records are:")
df.show(1)
val dfprev1 = df.select(col = "sno", "year", "StateAbbr")
dfprev1.show(1)
}
}
取出需要數量的認沽:
|sno|year|stateabbr| statedesc|cityname|geographiclevel
All the Columns names should be in lower case.
實際輸出:
Top Records are:
+---+----+---------+-------------+--------+---------------+----------+----------+--------+--------------------+---------------+---------------+--------------------+----------+--------------------+---------------------+--------------------------+-------------------+---------------+-----------+----------+---------+--------+---------+-------------------+
|sno|year|StateAbbr| StateDesc|CityName|GeographicLevel|DataSource| category|UniqueID| Measure|Data_Value_Unit|DataValueTypeID| Data_Value_Type|Data_Value|Low_Confidence_Limit|High_Confidence_Limit|Data_Value_Footnote_Symbol|Data_Value_Footnote|PopulationCount|GeoLocation|categoryID|MeasureId|cityFIPS|TractFIPS|Short_Question_Text|
+---+----+---------+-------------+--------+---------------+----------+----------+--------+--------------------+---------------+---------------+--------------------+----------+--------------------+---------------------+--------------------------+-------------------+---------------+-----------+----------+---------+--------+---------+-------------------+
| 1|2014| US|United States| null| US| BRFSS|Prevention| 59|Current lack of h...| %| AgeAdjPrv|Age-adjusted prev...| 14.9| 14.6| 15.2| null| null| 308745538| null| PREVENT| ACCESS2| null| null| Health Insurance|
+---+----+---------+-------------+--------+---------------+----------+----------+--------+--------------------+---------------+---------------+--------------------+----------+--------------------+---------------------+--------------------------+-------------------+---------------+-----------+----------+---------+--------+---------+-------------------+
only showing top 1 row
+---+----+---------+
|sno|year|StateAbbr|
+---+----+---------+
| 1|2014| US|
+---+----+---------+
only showing top 1 row
我明白了。謝謝你。 –