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2e5257372b
Because certain aggregates and concatenation requires results in
a certain order, this change allows specific control of the order
features are added to the aggregate during an expression evaluation.
E.g.
concatenate("Station",concatenator:=',', order_by:="Station")
will give a comma separated list of station names in alphabetical
order, rather than layer feature order.
Sponsored by SMEC/SJ
15 lines
765 B
Plaintext
15 lines
765 B
Plaintext
{
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"name": "array_agg",
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"type": "function",
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"description": "Returns an array of aggregated values from a field or expression.",
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"arguments": [
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{"arg": "expression", "description": "sub expression of field to aggregate"},
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{"arg": "group_by", "optional": true, "description": "optional expression to use to group aggregate calculations"},
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{"arg": "filter", "optional": true, "description": "optional expression to use to filter features used to calculate aggregate"},
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{"arg": "order_by", "optional": true, "description": "optional expression to use to order features used to calculate aggregate"}
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],
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"examples": [
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{ "expression": "array_agg(\"name\",group_by:=\"state\")", "returns":"list of name values, grouped by state field"}
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]
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}
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