使用pyspark从元组列表创建DataFrame [英] Create DataFrame from list of tuples using pyspark

问题描述

我正在使用使用simple-salesforce软件包从SFDC提取的数据. 我正在使用Python3编写脚本和Spark 1.5.2.

I am working with data extracted from SFDC using simple-salesforce package. I am using Python3 for scripting and Spark 1.5.2.

我创建了一个包含以下数据的rdd:

I created an rdd containing the following data:

[('Id', 'a0w1a0000003xB1A'), ('PackSize', 1.0), ('Name', 'A')]
[('Id', 'a0w1a0000003xAAI'), ('PackSize', 1.0), ('Name', 'B')]
[('Id', 'a0w1a00000xB3AAI'), ('PackSize', 30.0), ('Name', 'C')]
...

此数据在名为v_rdd的RDD中

This data is in RDD called v_rdd

我的模式如下:

StructType(List(StructField(Id,StringType,true),StructField(PackSize,StringType,true),StructField(Name,StringType,true)))

我正在尝试根据此RDD创建DataFrame:

I am trying to create DataFrame out of this RDD:

sqlDataFrame = sqlContext.createDataFrame(v_rdd, schema)

我打印我的DataFrame:

I print my DataFrame:

sqlDataFrame.printSchema()

并获得以下信息:

+--------------------+--------------------+--------------------+
|                  Id|  PackSize|                          Name|
+--------------------+--------------------+--------------------+
|[Ljava.lang.Objec...|[Ljava.lang.Objec...|[Ljava.lang.Objec...|
|[Ljava.lang.Objec...|[Ljava.lang.Objec...|[Ljava.lang.Objec...|
|[Ljava.lang.Objec...|[Ljava.lang.Objec...|[Ljava.lang.Objec...|

我希望看到这样的实际数据:

I am expecting to see actual data, like this:

+------------------+------------------+--------------------+
|                Id|PackSize|                          Name|
+------------------+------------------+--------------------+
|a0w1a0000003xB1A  |               1.0|       A            |
|a0w1a0000003xAAI  |               1.0|       B            |
|a0w1a00000xB3AAI  |              30.0|       C            |

能否请您帮助我确定我在这里做错了什么.

Can you please help me identify what I am doing wrong here.

我的Python脚本很长，我不确定人们浏览它会不会很方便，所以我只发布了我遇到问题的部分.

My Python script is long, I am not sure it would be convenient for people to sift through it, so I posted only parts I am having issue with.

提前感谢一吨！

推荐答案

嘿，下次您可以提供一个有效的示例.这样会更容易.

Hey could you next time provide a working example. That would be easier.

RDD的呈现方式基本上很奇怪，无法创建DataFrame.这是根据Spark文档创建DF的方式.

The way how your RDD is presented is basically weird to create a DataFrame. This is how you create a DF according to Spark Documentation.

>>> l = [('Alice', 1)]
>>> sqlContext.createDataFrame(l).collect()
[Row(_1=u'Alice', _2=1)]
>>> sqlContext.createDataFrame(l, ['name', 'age']).collect()
[Row(name=u'Alice', age=1)]

因此，对于您的示例，您可以按照以下方式创建所需的输出:

So concerning your example you can create your desired output like this way:

# Your data at the moment
data = sc.parallelize([ 
[('Id', 'a0w1a0000003xB1A'), ('PackSize', 1.0), ('Name', 'A')],
[('Id', 'a0w1a0000003xAAI'), ('PackSize', 1.0), ('Name', 'B')],
[('Id', 'a0w1a00000xB3AAI'), ('PackSize', 30.0), ('Name', 'C')]
    ])
# Convert to tuple
data_converted = data.map(lambda x: (x[0][1], x[1][1], x[2][1]))

# Define schema
schema = StructType([
    StructField("Id", StringType(), True),
    StructField("Packsize", StringType(), True),
    StructField("Name", StringType(), True)
])

# Create dataframe
DF = sqlContext.createDataFrame(data_converted, schema)

# Output
DF.show()
+----------------+--------+----+
|              Id|Packsize|Name|
+----------------+--------+----+
|a0w1a0000003xB1A|     1.0|   A|
|a0w1a0000003xAAI|     1.0|   B|
|a0w1a00000xB3AAI|    30.0|   C|
+----------------+--------+----+

希望这会有所帮助

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