spark dataframe有三列col1,col2,col3,对col1和col2进行minmax归一化处理,给出代码
时间: 2024-01-26 12:02:45 浏览: 25
下面是使用SparkSQL中的min和max函数完成DataFrame归一化的代码:
```python
from pyspark.ml.feature import MinMaxScaler
# 假设我们的DataFrame名为df,包含三列col1, col2, col3
cols_to_norm = ['col1', 'col2']
# 使用MinMaxScaler进行归一化,将结果存储到新列
scaler = MinMaxScaler(inputCol=cols_to_norm, outputCol='scaled_features')
df = scaler.fit(df).transform(df)
# 查看新列的结果
df.select('scaled_features', 'col1', 'col2', 'col3').show()
```
这将使用`MinMaxScaler`从DataFrame中选择列`col1`和`col2`来归一化,结果存储在名为`scaled_features`的新列中。调用的`fit()`方法将计算每列的最小和最大值,然后使用`transform()`方法将结果应用于DataFrame。最后,列`scaled_features`添加到DataFrame中并显示结果。
相关问题
spark dataframe有三列col1,col2,col3,对col1和col2进行minmax归一化处理,给出scala代码
可以使用Spark的MinMaxScaler进行归一化处理。具体实现的Scala代码如下:
```
import org.apache.spark.ml.feature.MinMaxScaler
import org.apache.spark.ml.feature.VectorAssembler
import org.apache.spark.sql.functions.col
val assembler = new VectorAssembler()
.setInputCols(Array("col1", "col2"))
.setOutputCol("features")
val scaler = new MinMaxScaler()
.setInputCol("features")
.setOutputCol("scaledFeatures")
val df = ... // 读取数据到DataFrame df 中
val processedDf = assembler.transform(df)
.select(col("col3"), col("scaledFeatures"))
val scaledDf = scaler.fit(processedDf).transform(processedDf)
.select(col("col3"), col("scaledFeatures").getItem(0).as("col1"), col("scaledFeatures").getItem(1).as("col2"))
```
上述代码先使用VectorAssembler将需要进行归一化处理的两列数据组合成一个特征向量,然后使用MinMaxScaler对该特征向量进行归一化处理。最终结果中包含第三列和归一化后的col1、col2列。
spark dataframe有三列col1,col2,col3,对col1和col2进行tfidf处理,然后分别进行minmax归一化处理,给出scala代码
下面是对col1和col2进行tfidf处理并分别进行minmax归一化处理的scala代码:
```
import org.apache.spark.ml.feature.{HashingTF, IDF, MaxAbsScaler}
import org.apache.spark.ml.linalg.DenseVector
import org.apache.spark.sql.functions.{col, udf}
import org.apache.spark.sql.types.DoubleType
// 假设输入的dataframe名字为df,同时假设col1和col2是字符串类型
val hashingTF = new HashingTF().setInputCol("text").setOutputCol("rawFeatures").setNumFeatures(10000)
val tf = hashingTF.transform(df)
val idf = new IDF().setInputCol("rawFeatures").setOutputCol("features")
val idfModel = idf.fit(tf)
val tfidf = idfModel.transform(tf).withColumnRenamed("features", "features_unscaled")
val udf_v_to_dv = udf((v: org.apache.spark.ml.linalg.Vector) => new DenseVector(v.toArray), org.apache.spark.sql.types.DataTypes.createArrayType(DoubleType))
val udf_dv_to_v = udf((dv: DenseVector) => org.apache.spark.ml.linalg.Vectors.dense(dv.toArray), org.apache.spark.sql.types.DataTypes.createArrayType(org.apache.spark.sql.types.DataTypes.DoubleType))
val minmaxScaler1 = new MaxAbsScaler().setInputCol("features_unscaled").setOutputCol("features_scaled_col1")
val tfidfScaled1 = minmaxScaler1.fit(tfidf).transform(tfidf).withColumn("features_scaled_col1", udf_v_to_dv(col("features_scaled_col1")))
val minmaxScaler2 = new MaxAbsScaler().setInputCol("features_unscaled").setOutputCol("features_scaled_col2")
val tfidfScaled2 = minmaxScaler2.fit(tfidf).transform(tfidf).withColumn("features_scaled_col2", udf_v_to_dv(col("features_scaled_col2")))
tfidfScaled2.select("features_scaled_col1", "features_scaled_col2").withColumn("features_scaled_col1", udf_dv_to_v(col("features_scaled_col1"))).withColumn("features_scaled_col2", udf_dv_to_v(col("features_scaled_col2")))
```