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49 lines
2.3 KiB
Markdown
49 lines
2.3 KiB
Markdown
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---
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toc_priority: 46
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toc_title: Working with maps
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---
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# Functions for maps {#functions-for-working-with-tuple-maps}
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## mapAdd(Tuple(Array, Array), Tuple(Array, Array) [, ...]) {#function-mapadd}
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Collect all the keys and sum corresponding values.
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Arguments are tuples of two arrays, where items in the first array represent keys, and the second array
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contains values for the each key.
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All key arrays should have same type, and all value arrays should contain items which are promotable to the one type (Int64, UInt64 or Float64).
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The common promoted type is used as a type for the result array.
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Returns one tuple, where the first array contains the sorted keys and the second array contains values.
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```sql
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SELECT mapAdd(([toUInt8(1), 2], [1, 1]), ([toUInt8(1), 2], [1, 1])) as res, toTypeName(res) as type;
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```
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```text
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┌─res───────────┬─type───────────────────────────────┐
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│ ([1,2],[2,2]) │ Tuple(Array(UInt8), Array(UInt64)) │
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└───────────────┴────────────────────────────────────┘
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```
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## mapSubtract(Tuple(Array, Array), Tuple(Array, Array) [, ...]) {#function-mapsubtract}
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Collect all the keys and subtract corresponding values.
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Arguments are tuples of two arrays, where items in the first array represent keys, and the second array
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contains values for the each key.
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All key arrays should have same type, and all value arrays should contain items which are promotable to the one type (Int64, UInt64 or Float64).
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The common promoted type is used as a type for the result array.
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Returns one tuple, where the first array contains the sorted keys and the second array contains values.
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```sql
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SELECT mapSubtract(([toUInt8(1), 2], [toInt32(1), 1]), ([toUInt8(1), 2], [toInt32(2), 1])) as res, toTypeName(res) as type;
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```
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```text
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┌─res────────────┬─type──────────────────────────────┐
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│ ([1,2],[-1,0]) │ Tuple(Array(UInt8), Array(Int64)) │
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└────────────────┴───────────────────────────────────┘
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````
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