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https://issues.apache.org/jira/browse/MAHOUT-1856?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15833743#comment-15833743
]
ASF GitHub Bot commented on MAHOUT-1856:
----------------------------------------
Github user andrewpalumbo commented on a diff in the pull request:
https://github.com/apache/mahout/pull/246#discussion_r97236955
--- Diff:
math-scala/src/main/scala/org/apache/mahout/math/algorithms/transformer/StandardScaler.scala
---
@@ -0,0 +1,119 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.mahout.math.algorithms.transformer
+
+import org.apache.mahout.math.drm
+
+import org.apache.mahout.math.scalabindings._
+
+import org.apache.mahout.math.scalabindings.RLikeVectorOps
+import org.apache.mahout.math.{Vector => MahoutVector}
+
+import org.apache.mahout.math.scalabindings.RLikeOps._
+import org.apache.mahout.math.scalabindings._
+import org.apache.mahout.math.scalabindings.RLikeVectorOps
+import org.apache.mahout.math.scalabindings.MatrixOps
+
+import org.apache.mahout.math._
+import org.apache.mahout.math.scalabindings._
+import org.apache.mahout.math.drm._
+import org.apache.mahout.math.scalabindings.RLikeOps._
+import org.apache.mahout.math.drm.RLikeDrmOps._
+
+
+import org.apache.mahout.math.Matrix
+
+import collection._
+import JavaConversions._
+
+import Math.sqrt
+
+import scala.reflect.{ClassTag,classTag}
+
+/**
+ * Scales columns to mean 0 and unit variance
+ */
+class StandardScaler extends Transformer{
+ var meanVec: MahoutVector = _
+ var variance: MahoutVector = _
+ var stdev: MahoutVector = _
+ var summary = ""
+
+ def fit[K](input: DrmLike[K]) = {
+ val mNv = dcolMeanVars(input)
+ meanVec = mNv._1
+ variance = mNv._2
+ stdev = mNv._2.sqrt
+ isFit = true
+
+ }
+
+ def transform[K: ClassTag](input: DrmLike[K]): DrmLike[K] = {
+
+ if (!isFit) {
+ //throw an error
--- End diff --
As well, I think that this could be another argument for moving
Hyperparamaters into `fit(...)`, e.g. If for some reason we wanted to
standardize on N(mean = 0, stdDev = 2), we could still call `StandardScaler`
and `fit (Map["mu" -> 0, "sigma" ->2])`:
```
val drmStandardized = StandardScaler(unscaledDrm).fit(Map["mu" -> 0,
"sigma" ->2]).transform()
```
> Create a framework for new Mahout Clustering, Classification, and
> Optimization Algorithms
> ------------------------------------------------------------------------------------------
>
> Key: MAHOUT-1856
> URL: https://issues.apache.org/jira/browse/MAHOUT-1856
> Project: Mahout
> Issue Type: New Feature
> Affects Versions: 0.12.1
> Reporter: Andrew Palumbo
> Assignee: Trevor Grant
> Priority: Critical
> Fix For: 0.13.0
>
>
> To ensure that Mahout does not become "A loose bag of algorithms", Create
> basic traits with funtions common to each class of algorithm.
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