我正在研究一种机器学习算法来预测以太坊的价格。我已经有一个小的数据集，我正在做预测。我可以在终端机上打印预测，我可以看到它们。但是，我无法将它们保存为text/csv文件。这是我的密码

from pyspark.sql.types import *
from pyspark.sql import Row, SparkSession
from pyspark.mllib.util import MLUtils
from pyspark.ml.linalg import Vectors
from pyspark.ml.feature import VectorAssembler

from pyspark.ml.regression import LinearRegression
from pyspark.sql.types import DateType

from pyspark import SparkContext
import pyspark
import datetime

sc = pyspark.SparkContext()
spark = SparkSession.builder.appName('Ethereum').getOrCreate()
 #get csv file as a DataFram object
data = spark.read.csv('hdfs://andromeda.student.eecs.qmul.ac.uk/user/cln31/ethereum', header=True,inferSchema=True)

# DataFrame type

data = data.select(data.date.cast("int"),
                    data.PriceBTC.cast("float"),
                    data.PriceUSD.cast("float"),
                    data.TxCnt.cast("float"),
                    data.TxTfrValMedUSD.cast("float"),
                    data.CapMrktCurUSD.cast("float"),
                    data.IssContUSD.cast("float"),
                    data.TxTfrValMeanUSD.cast("float"),
                    data.TxTfrValUSD.cast("float"))

data.printSchema()

featureassembler=VectorAssembler(inputCols=["date","TxTfrValMedUSD","CapMrktCurUSD","TxCnt","TxTfrValUSD", "IssContUSD", "TxTfrValMeanUSD"],outputCol="Independent Features")
output = featureassembler.setHandleInvalid("skip").transform(data)
output.show()

output.select("Independent Features").show()

finalized_data=output.select("Independent Features","PriceUSD")
finalized_data.show()

train_data,test_data=finalized_data.randomSplit([0.75,0.25])

regressor=LinearRegression(featuresCol='Independent Features', labelCol='PriceUSD')
regressor=regressor.fit(train_data)

test_data1 = output.filter(data.date >= 1455408000) #2016.02.14
test_data1 = test_data1.filter(test_data1.date <= 1561852800) #2019.06.30

test_data1 = test_data1.select("Independent Features","PriceUSD")

test_data1.show()

pred_results=regressor.evaluate(test_data1)
pred_results.predictions.describe().show()

pred_results.predictions.write.csv("partCOut.csv")

我基本上是想保存pred\u results.predictions的输出。这是我得到的错误：
pyspark.sql.utils.analysisexception:u'csv数据源不支持 struct<type:tinyint,size:int,indices:array<int>,values:array<double>> 数据类型。；'