How to implement AVG and COUNT of GroupAggregate?

[kerne...@gmail.com]

Hi,

    I want to implement AVG and COUNT of GroupAggregate,but i found there is no AggregationOperator about them.So what should I do ? Thank you very much!

[Piotr Tabor]

There is SUM and COUNT. Search for SUM here to get an example: https://code.google.com/p/supersonic/source/browse/supersonic/cursor/core/aggregate_clusters_test.cc. 

If you want to compute AVG you need to do SUM(x)/COUNT(x)... It's more efficient that way. 

On Wed, Apr 2, 2014 at 11:20 AM, <kerne...@gmail.com> wrote:

Hi,

    I want to implement AVG and COUNT of GroupAggregate,but i found there is no AggregationOperator about them.So what should I do ? Thank you very much!

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[kerne...@gmail.com]

Yes,I know the example of the SUM,but I don`t know how to implement the SUM(x)/COUNT(x).like this?

 specification-> AddAggregation(SUM/COUNT, "L_QUANTITY", "avg_qty");

and when I use the COUNT,

 specification-> AddAggregation(COUNT, "L_QUANTITY", "sum_qty");

there is a error:

'COUNT' was not declared in this scope.

and I can`t find the COUNT in aggregation_operators.h which I can find SUM in it.Thank you !

在 2014年4月2日星期三UTC+8下午5时20分01秒，kerne...@gmail.com写道：

[kerne...@gmail.com]

sorry,the COUNT`s problem i have sovled，it is because of the namespace,but the SUM(x)/COUNT(x) I still don`t know how to implement.Thank you for helping!

在 2014年4月2日星期三UTC+8下午5时20分01秒，kerne...@gmail.com写道：

[Milosz Tanski]

Just add a compute operation at the end of the Operation chain. Feed it an expression that will project all Attributes (eg... COUNT and SUM) and add another expression that will do a division of Attribute 1 (sum) by Attribute 0 (count). This should give you a result of (COUNT, SUM, AVG).

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