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[SPARK-7687] [SQL] DataFrame.describe() should cast all aggregates to String #6218

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[SPARK-7687] [SQL] DataFrame.describe() should cast all aggregates to String #6218

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307ecbf
Add failing regression test for SPARK-7687
JoshRosen May 17, 2015
f206580
Cast to double to fix SPARK-7687
JoshRosen May 17, 2015
2974bd5
Cast to string type instead
JoshRosen May 18, 2015
146b615
Fix R test.
JoshRosen May 18, 2015
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10 changes: 5 additions & 5 deletions R/pkg/inst/tests/test_sparkSQL.R
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Original file line number Diff line number Diff line change
Expand Up @@ -757,12 +757,12 @@ test_that("parquetFile works with multiple input paths", {
test_that("describe() on a DataFrame", {
df <- jsonFile(sqlCtx, jsonPath)
stats <- describe(df, "age")
expect_true(collect(stats)[1, "summary"] == "count")
expect_true(collect(stats)[2, "age"] == 24.5)
expect_true(collect(stats)[3, "age"] == 5.5)
expect_equal(collect(stats)[1, "summary"], "count")
expect_equal(collect(stats)[2, "age"], "24.5")
expect_equal(collect(stats)[3, "age"], "5.5")
stats <- describe(df)
expect_true(collect(stats)[4, "name"] == "Andy")
expect_true(collect(stats)[5, "age"] == 30.0)
expect_equal(collect(stats)[4, "name"], "Andy")
expect_equal(collect(stats)[5, "age"], "30")
})

unlink(parquetPath)
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6 changes: 3 additions & 3 deletions sql/core/src/main/scala/org/apache/spark/sql/DataFrame.scala
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Expand Up @@ -1063,7 +1063,7 @@ class DataFrame private[sql](

val ret: Seq[Row] = if (outputCols.nonEmpty) {
val aggExprs = statistics.flatMap { case (_, colToAgg) =>
outputCols.map(c => Column(colToAgg(Column(c).expr)).as(c))
outputCols.map(c => Column(Cast(colToAgg(Column(c).expr), StringType)).as(c))
}

val row = agg(aggExprs.head, aggExprs.tail: _*).head().toSeq
Expand All @@ -1077,9 +1077,9 @@ class DataFrame private[sql](
statistics.map { case (name, _) => Row(name) }
}

// The first column is string type, and the rest are double type.
// All columns are string type
val schema = StructType(
StructField("summary", StringType) :: outputCols.map(StructField(_, DoubleType))).toAttributes
StructField("summary", StringType) :: outputCols.map(StructField(_, StringType))).toAttributes
LocalRelation(schema, ret)
}

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17 changes: 11 additions & 6 deletions sql/core/src/test/scala/org/apache/spark/sql/DataFrameSuite.scala
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Expand Up @@ -370,14 +370,14 @@ class DataFrameSuite extends QueryTest {
("Amy", 24, 180)).toDF("name", "age", "height")

val describeResult = Seq(
Row("count", 4, 4),
Row("mean", 33.0, 178.0),
Row("stddev", 16.583123951777, 10.0),
Row("min", 16, 164),
Row("max", 60, 192))
Row("count", "4", "4"),
Row("mean", "33.0", "178.0"),
Row("stddev", "16.583123951777", "10.0"),
Row("min", "16", "164"),
Row("max", "60", "192"))

val emptyDescribeResult = Seq(
Row("count", 0, 0),
Row("count", "0", "0"),
Row("mean", null, null),
Row("stddev", null, null),
Row("min", null, null),
Expand All @@ -388,6 +388,11 @@ class DataFrameSuite extends QueryTest {
val describeTwoCols = describeTestData.describe("age", "height")
assert(getSchemaAsSeq(describeTwoCols) === Seq("summary", "age", "height"))
checkAnswer(describeTwoCols, describeResult)
// All aggregate value should have been cast to string
describeTwoCols.collect().foreach { row =>
assert(row.get(1).isInstanceOf[String], "expected string but found " + row.get(1).getClass)
assert(row.get(2).isInstanceOf[String], "expected string but found " + row.get(2).getClass)
}

val describeAllCols = describeTestData.describe()
assert(getSchemaAsSeq(describeAllCols) === Seq("summary", "age", "height"))
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