Christos Iraklis Tsatsoulis created SPARK-12372:
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Summary: Unary operator "-" fails for MLlib vectors
Key: SPARK-12372
URL: https://issues.apache.org/jira/browse/SPARK-12372
Project: Spark
Issue Type: Bug
Components: MLlib, PySpark
Affects Versions: 1.5.2
Reporter: Christos Iraklis Tsatsoulis
Consider the following snippet in pyspark 1.5.2:
{code:none}
>>> from pyspark.mllib.linalg import Vectors
>>> x = Vectors.dense([0.0, 1.0, 0.0, 7.0, 0.0])
>>> x
DenseVector([0.0, 1.0, 0.0, 7.0, 0.0])
>>> -x
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: func() takes exactly 2 arguments (1 given)
>>> y = Vectors.dense([2.0, 0.0, 3.0, 4.0, 5.0])
>>> y
DenseVector([2.0, 0.0, 3.0, 4.0, 5.0])
>>> x-y
DenseVector([-2.0, 1.0, -3.0, 3.0, -5.0])
>>> -y+x
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: func() takes exactly 2 arguments (1 given)
>>> -1*x
DenseVector([-0.0, -1.0, -0.0, -7.0, -0.0])
{code}
Clearly, the unary operator {{-}} (minus) for vectors fails, giving errors for
expressions like {{-x}} and {{-y+x}}, despite the fact that {{x-y}} behaves as
expected.
The last operation, {{-1*x}}, although mathematically "correct", includes minus
signs for the zero entries, which again is normally not expected.
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