How to convert Spark RDD to pandas dataframe in ipython?

问题

I have a RDD and I want to convert it to pandas dataframe. I know that to convert and RDD to a normal dataframe we can do

df = rdd1.toDF()

But I want to convert the RDD to pandas dataframe and not a normal dataframe. How can I do it?

回答1:

You can use function toPandas():

Returns the contents of this DataFrame as Pandas pandas.DataFrame.

This is only available if Pandas is installed and available.

>>> df.toPandas()  
   age   name
0    2  Alice
1    5    Bob

回答2:

You'll have to use a Spark DataFrame as an intermediary step between your RDD and the desired Pandas DataFrame.

For example, let's say I have a text file, flights.csv, that has been read in to an RDD:

flights = sc.textFile('flights.csv')

You can check the type:

type(flights)
<class 'pyspark.rdd.RDD'>

If you just use toPandas() on the RDD, it won't work. Depending on the format of the objects in your RDD, some processing may be necessary to go to a Spark DataFrame first. In the case of this example, this code does the job:

# RDD to Spark DataFrame
sparkDF = flights.map(lambda x: str(x)).map(lambda w: w.split(',')).toDF()

#Spark DataFrame to Pandas DataFrame
pdsDF = sparkDF.toPandas()

You can check the type:

type(pdsDF)
<class 'pandas.core.frame.DataFrame'>

回答3:

I recommend a fast version of toPandas by joshlk

<script src="https://gist.github.com/joshlk/871d58e01417478176e7.js"></script>

来源：https://stackoverflow.com/questions/34817549/how-to-convert-spark-rdd-to-pandas-dataframe-in-ipython