[SPARK-11535][ML] handling empty string in StringIndexer #11575
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Can one of the admins verify this patch? |
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| test("StringIndexer on column with empty string values") { | ||
| val data = sc.parallelize(Seq((0, "a"), (1, ""), (2, "c"), (3, "a"), (4, "a"), (5, "c")), 2) | ||
| val df = sqlContext.createDataFrame(data).toDF("id", "label") |
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These two lines could be written as:
Seq((0, "a"), (1, ""), (2, "c"), (3, "a"), (4, "a"), (5, "c")).toDF("id", "label")
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@jaceklaskowski Yes you are right. I'm using Intellij ide, which requires you add import sqlContext.implicits._ in order to use syntax mentioned by you. Thus I was avoiding that.
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What changes were proposed in this pull request?
Replacing "" (not null) with string "EMPTY_STRING" in StringIndexer. Another approach is to use "0" (or next available integer), but it may have performance issues when input column has integer values say (0 to 100000). We can use another string to replace "" values if "EMPTY_STRING" is commonly used.
How was this patch tested?
unit tests