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add docs and simplify the code

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memo 2019-10-22 10:23:07 +08:00
parent ef09cedbb8
commit 645bcdacae
2 changed files with 20 additions and 37 deletions
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38
dbms/src/Functions/array/arrayCompact.cpp
View File

@ -3,7 +3,6 @@
#include "FunctionArrayMapped.h"
#include <Functions/FunctionFactory.h>
namespace DB
{
/// arrayCompact(['a', 'a', 'b', 'b', 'a']) = ['a', 'b', 'a'] - compact arrays
@ -14,6 +13,7 @@ namespace DB
struct ArrayCompactImpl
{
static bool useDefaultImplementationForConstants() { return true; }
static bool needBoolean() { return false; }
static bool needExpression() { return false; }
static bool needOneArray() { return false; }
@ -41,40 +41,7 @@ namespace DB
const ColumnVector<Element> * column = checkAndGetColumn<ColumnVector<Element>>(&*mapped);
if (!column)
{
const ColumnConst * column_const = checkAndGetColumnConst<ColumnVector<Element>>(&*mapped);
if (!column_const)
return false;
const Element x = column_const->template getValue<Element>();
const IColumn::Offsets & offsets = array.getOffsets();
auto column_data = ColumnVector<Result>::create(column_const->size());
typename ColumnVector<Result>::Container & res_values = column_data->getData();
auto column_offsets = ColumnArray::ColumnOffsets::create(offsets.size());
IColumn::Offsets & res_offsets = column_offsets->getData();
size_t res_pos = 0;
size_t pos = 0;
for (size_t i = 0; i < offsets.size(); ++i)
{
if (pos < offsets[i])
{
res_values[res_pos] = x;
for (++pos, ++res_pos; pos < offsets[i]; ++pos)
{
res_values[res_pos++] = x;
}
}
res_offsets[i] = res_pos;
}
for (size_t i = 0; i < column_data->size() - res_pos; ++i)
{
res_values.pop_back();
}
res_ptr = ColumnArray::create(std::move(column_data), std::move(column_offsets));
return true;
}
return false;
const IColumn::Offsets & offsets = array.getOffsets();
const typename ColumnVector<Element>::Container & data = column->getData();
@ -138,4 +105,3 @@ namespace DB
}
}

19
docs/en/query_language/functions/array_functions.md
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@ -789,5 +789,22 @@ SELECT arrayReverse([1, 2, 3])
Synonym for ["arrayReverse"](#array_functions-arrayreverse)
[Original article](https://clickhouse.yandex/docs/en/query_language/functions/array_functions/) <!--hide-->
## arrayCompact(arr) {#array_functions-arraycompact}
Takes an array, returns an array with elements that are different between two adjacent elements.
Example:
```sql
SELECT arrayCompact([1, 2, 2, 3, 2, 3, 3])
```
```text
┌─arrayDistinct([1, 2, 2, 3, 2, 3, 3])─┐
│ [1,2,3,2,3] │
└──────────────────────────────────────┘
```
##