[jira] [Closed] (SPARK-12372) Unary operator "-" fails for MLlib vectors

["Joseph K. Bradley (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-12372?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Joseph K. Bradley closed SPARK-12372.
-------------------------------------
    Resolution: Not A Problem

> 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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