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Merged
rongrong merged 1 commit into from
Jun 16, 2021
Merged

Add SQL function array_frequency #16198

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10 changes: 10 additions & 0 deletions presto-docs/src/main/sphinx/functions/array.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,16 @@ Array Functions

Returns an array of elements in ``x`` but not in ``y``, without duplicates.

.. function:: array_frequency(array(bigint)) -> map(bigint, int)

Returns a map: keys are the unique elements in the ``array``, values are how many times the key appears.
Ignores null elements. Empty array returns empty map.

.. function:: array_frequency(array(varchar)) -> map(varchar, int)

Returns a map: keys are the unique elements in the ``array``, values are how many times the key appears.
Ignores null elements. Empty array returns empty map.

.. function:: array_intersect(x, y) -> array

Returns an array of the elements in the intersection of ``x`` and ``y``, without duplicates.
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26 changes: 26 additions & 0 deletions ...-main/src/main/java/com/facebook/presto/operator/scalar/sql/ArrayArithmeticFunctions.java
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Expand Up @@ -52,4 +52,30 @@ public static String arrayAverage()
"(s, x) -> IF(x IS NOT NULL, (s[1] + x, s[2] + 1), s), " +
"s -> if(s[2] = 0, cast(null as double), s[1] / cast(s[2] as double)))";
}

@SqlInvokedScalarFunction(value = "array_frequency", deterministic = true, calledOnNullInput = false)
@Description("Returns the frequency of all array elements as a map.")
@SqlParameter(name = "input", type = "array(bigint)")
@SqlType("map(bigint, int)")
public static String arrayFrequencyBigint()
{
return "RETURN reduce(" +
"input," +
"MAP()," +
"(m, x) -> IF (x IS NOT NULL, MAP_CONCAT(m,MAP_FROM_ENTRIES(ARRAY[ROW(x, COALESCE(ELEMENT_AT(m,x) + 1, 1))])), m)," +
"m -> m)";
}

@SqlInvokedScalarFunction(value = "array_frequency", deterministic = true, calledOnNullInput = false)
@Description("Returns the frequency of all array elements as a map.")
@SqlParameter(name = "input", type = "array(varchar)")
@SqlType("map(varchar, int)")
public static String arrayFrequencyVarchar()
{
return "RETURN reduce(" +
"input," +
"MAP()," +
"(m, x) -> IF (x IS NOT NULL, MAP_CONCAT(m,MAP_FROM_ENTRIES(ARRAY[ROW(x, COALESCE(ELEMENT_AT(m,x) + 1, 1))])), m)," +
"m -> m)";
}
}
56 changes: 56 additions & 0 deletions ...n/src/test/java/com/facebook/presto/operator/scalar/sql/TestArrayArithmeticFunctions.java
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Expand Up @@ -13,11 +13,20 @@
*/
package com.facebook.presto.operator.scalar.sql;

import com.facebook.presto.common.type.MapType;
import com.facebook.presto.common.type.TestRowType;
import com.facebook.presto.common.type.TypeSignature;
import com.facebook.presto.metadata.FunctionAndTypeManager;
import com.facebook.presto.operator.scalar.AbstractTestFunctions;
import com.google.common.collect.ImmutableMap;
import org.testng.annotations.Test;

import static com.facebook.presto.common.block.MethodHandleUtil.methodHandle;
import static com.facebook.presto.common.type.BigintType.BIGINT;
import static com.facebook.presto.common.type.DoubleType.DOUBLE;
import static com.facebook.presto.common.type.IntegerType.INTEGER;
import static com.facebook.presto.common.type.VarcharType.VARCHAR;
import static com.facebook.presto.metadata.FunctionAndTypeManager.createTestFunctionAndTypeManager;

public class TestArrayArithmeticFunctions
extends AbstractTestFunctions
Expand Down Expand Up @@ -65,4 +74,51 @@ public void testArrayAverage()
assertFunction("array_average(array[null, null])", DOUBLE, null);
assertFunction("array_average(null)", DOUBLE, null);
}

@Test
public void testArrayFrequencyBigint()
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@prithvip prithvip Jun 11, 2021

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I think we should also add tests for the empty array case, and for nulls in the array.

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@rongrong rongrong Jun 15, 2021

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Let's also add test for empty array as @prithvip suggested. array_frequency(cast(array[] as array(bigint). Also, for bigint / varchar, either use all upper case or all lower case. SQL is case in sensitive, I think here you can use all lower case.

{
FunctionAndTypeManager functionAndTypeManager = createTestFunctionAndTypeManager();
MapType type = new MapType(BIGINT,
INTEGER,
methodHandle(TestRowType.class, "throwUnsupportedOperation"),
methodHandle(TestRowType.class, "throwUnsupportedOperation"));
TypeSignature typeSignature = TypeSignature.parseTypeSignature(type.getDisplayName());

assertFunction("array_frequency(cast(null as array(bigint)))", functionAndTypeManager.getType(typeSignature), null);
assertFunction("array_frequency(cast(array[] as array(bigint)))", functionAndTypeManager.getType(typeSignature), ImmutableMap.of());
assertFunction("array_frequency(array[cast(null as bigint), cast(null as bigint), cast(null as bigint)])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of());
assertFunction("array_frequency(array[cast(null as bigint), bigint '1'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(1L, 1));
assertFunction("array_frequency(array[cast(null as bigint), bigint '1', bigint '3', cast(null as bigint), bigint '1', bigint '3', cast(null as bigint)])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(1L, 2, 3L, 2));
assertFunction("array_frequency(array[bigint '1', bigint '1', bigint '2', bigint '2', bigint '3', bigint '1', bigint '3', bigint '2'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(1L, 3, 2L, 3, 3L, 2));
assertFunction("array_frequency(array[bigint '45'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(45L, 1));
assertFunction("array_frequency(array[bigint '-45'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(-45L, 1));
assertFunction("array_frequency(array[bigint '1', bigint '3', bigint '1', bigint '3'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(1L, 2, 3L, 2));
assertFunction("array_frequency(array[bigint '3', bigint '1', bigint '3',bigint '1'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(1L, 2, 3L, 2));
assertFunction("array_frequency(array[bigint '4',bigint '3',bigint '3',bigint '2',bigint '2',bigint '2',bigint '1',bigint '1',bigint '1',bigint '1'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(1L, 4, 2L, 3, 3L, 2, 4L, 1));
assertFunction("array_frequency(array[bigint '3', bigint '3', bigint '2', bigint '2', bigint '5', bigint '5', bigint '1', bigint '1'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(1L, 2, 2L, 2, 3L, 2, 5L, 2));
}

@Test
public void testArrayFrequencyVarchar()
{
FunctionAndTypeManager functionAndTypeManager = createTestFunctionAndTypeManager();

MapType type = new MapType(VARCHAR,
INTEGER,
methodHandle(TestRowType.class, "throwUnsupportedOperation"),
methodHandle(TestRowType.class, "throwUnsupportedOperation"));
TypeSignature typeSignature = TypeSignature.parseTypeSignature(type.getDisplayName());

assertFunction("array_frequency(cast(null as array(varchar)))", functionAndTypeManager.getType(typeSignature), null);
assertFunction("array_frequency(cast(array[] as array(varchar)))", functionAndTypeManager.getType(typeSignature), ImmutableMap.of());
assertFunction("array_frequency(array[cast(null as varchar), cast(null as varchar), cast(null as varchar)])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of());
assertFunction("array_frequency(array[varchar 'z', cast(null as varchar)])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of("z", 1));
assertFunction("array_frequency(array[varchar 'a', cast(null as varchar), varchar 'b', cast(null as varchar), cast(null as varchar) ])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of("a", 1, "b", 1));
assertFunction("array_frequency(array[varchar 'a', varchar 'b', varchar 'a', varchar 'a', varchar 'a'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of("a", 4, "b", 1));
assertFunction("array_frequency(array[varchar 'a', varchar 'b', varchar 'a', varchar 'b', varchar 'c'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of("a", 2, "b", 2, "c", 1));
assertFunction("array_frequency(array[varchar 'y', varchar 'p'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of("p", 1, "y", 1));
assertFunction("array_frequency(array[varchar 'a', varchar 'a', varchar 'p'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of("p", 1, "a", 2));
assertFunction("array_frequency(array[varchar 'z'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of("z", 1));
}
}