pyspark : NameError: name 'spark' is not defined

Question

I am copying the pyspark.ml example from the official document website: http://spark.apache.org/docs/latest/api/python/pyspark.ml.html#pyspark.ml.Transformer

Answer 1

You can add

from pyspark.context import SparkContext
from pyspark.sql.session import SparkSession
sc = SparkContext('local')
spark = SparkSession(sc)

to the begining of your codes to define a SparkSession, then the spark.createDataFrame() should work.

Answer 2

Answer by 率怀一 is good and will work for the first time. But the second time you try it, it will throw the following exception :

ValueError: Cannot run multiple SparkContexts at once; existing SparkContext(app=pyspark-shell, master=local) created by __init__ at <ipython-input-3-786525f7559f>:10 

There are two ways to avoid it.

1) Using SparkContext.getOrCreate() instead of SparkContext():

from pyspark.context import SparkContext
from pyspark.sql.session import SparkSession
sc = SparkContext.getOrCreate()
spark = SparkSession(sc)

2) Using sc.stop() in the end, or before you start another SparkContext.

Answer 3

Since you are calling createDataFrame(), you need to do this:

df = sqlContext.createDataFrame(data, ["features"])

instead of this:

df = spark.createDataFrame(data, ["features"])

spark stands there as the sqlContext.

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In general, some people have that as sc, so if that didn't work, you could try:

df = sc.createDataFrame(data, ["features"])