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From "Joseph K. Bradley (JIRA)" <j...@apache.org>
Subject [jira] [Created] (SPARK-6857) Python SQL schema inference should support numpy types
Date Sat, 11 Apr 2015 00:48:12 GMT
Joseph K. Bradley created SPARK-6857:
----------------------------------------

             Summary: Python SQL schema inference should support numpy types
                 Key: SPARK-6857
                 URL: https://issues.apache.org/jira/browse/SPARK-6857
             Project: Spark
          Issue Type: Improvement
          Components: MLlib, PySpark, SQL
    Affects Versions: 1.3.0
            Reporter: Joseph K. Bradley


If you try to use SQL's schema inference to create a DataFrame out of a list or RDD of numpy
types (such as numpy.float64), SQL will not recognize the numpy types.  It would be handy
if it did.

E.g.:
{code}
import numpy
from collections import namedtuple
from pyspark.sql import SQLContext
MyType = namedtuple('MyType', 'x')
myValues = map(lambda x: MyType(x), numpy.random.randint(100, size=10))
sqlContext = SQLContext(sc)
data = sqlContext.createDataFrame(myValues)
{code}

The above code fails with:
{code}
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/josephkb/spark/python/pyspark/sql/context.py", line 331, in createDataFrame
    return self.inferSchema(data, samplingRatio)
  File "/Users/josephkb/spark/python/pyspark/sql/context.py", line 205, in inferSchema
    schema = self._inferSchema(rdd, samplingRatio)
  File "/Users/josephkb/spark/python/pyspark/sql/context.py", line 160, in _inferSchema
    schema = _infer_schema(first)
  File "/Users/josephkb/spark/python/pyspark/sql/types.py", line 660, in _infer_schema
    fields = [StructField(k, _infer_type(v), True) for k, v in items]
  File "/Users/josephkb/spark/python/pyspark/sql/types.py", line 637, in _infer_type
    raise ValueError("not supported type: %s" % type(obj))
ValueError: not supported type: <type 'numpy.int64'>
{code}

But if we cast to int (not numpy types) first, it's OK:
{code}
myNativeValues = map(lambda x: MyType(int(x.x)), myValues)
data = sqlContext.createDataFrame(myNativeValues) # OK
{code}




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