Hi Giacomo,
a DataSet is just a logical construct to define data flows. It does not
actually hold any data.
Here's a code snippet that sums some Integers and returns the result to the
client program:
DataSet<Integer> data = ...
// sum
DataSet<Integer> sum = data.reduce(new ReduceFunction<Integer>() {
public Integer reduce(Integer v1, Integer v2) { return v1+v2; }
}
// fetch result back
List<Integer> values = sum.collect(); // returns a list because the DataSet
might contain more elements
Let me know, if you have more questions.
Cheers, Fabian
2015-04-29 10:48 GMT+02:00 Giacomo Licari <[email protected]>:
> Hi Fabian,
> is possible to assign the reduce result to a POJO variable?
> At the moment inside the reduce function I'm passing the final count to a
> global variable.
>
> Example:
> double X = DataSet<Double> myDataSet.GroupReduce(new MyReducer());
>
> On Tue, Apr 28, 2015 at 9:54 PM, Fabian Hueske <[email protected]> wrote:
>
>> You can also use Reduce to compute a sum on any data type (e.g., an
>> Integer field in a POJO).
>>
>> 2015-04-28 15:25 GMT+02:00 Maximilian Michels <[email protected]>:
>>
>>> Hi Giacomo,
>>>
>>> If you have your data stored in a Tuple inside a DataSet, then a call to
>>> dataSet.sum(int field) should do it.
>>>
>>> See Aggregation under
>>> http://ci.apache.org/projects/flink/flink-docs-master/apis/programming_guide.html#transformations
>>>
>>> Best,
>>> Max
>>>
>>> On Tue, Apr 28, 2015 at 2:52 PM, Giacomo Licari <
>>> [email protected]> wrote:
>>>
>>>> Hi Guys,
>>>> how can obtain the sum of all items (integer or double) in a DataSet?
>>>>
>>>> Do I have to use Flink Iterators? And how?
>>>>
>>>> Thank you,
>>>> Giacomo
>>>>
>>>
>>>
>>
>
