I am missing the concatenate function in Radoop like in Rapidminer Studio. In Studio I can concat grouped Values with the Aggregate Operator. In Radoop is this function not available. How can I illustrate this in Radoop?
true, the Radoop Aggregate does not have a built-in concatenate option currently.
You can use the Hive Script operator in this case with a modified version of the following script that demonstrates group concatenation on the Golf sample dataset (from the Sample repository), explanation is below.
CREATE VIEW ##outputtable## AS SELECT play, concat_ws(', ', sort_array(collect_set(outlook))) outlook_values FROM ##inputtable1## GROUP BY play
The result will look like this:
The aggregation function here is collect_set that collects the distinct values from the outlook column. If you need all values instead of just the distinct values, use collect_list instead. The sort_array function is only required, if you want the value list to be deterministic and sorted. If not, it can be omitted. The concat_ws function concatenates the values from an array with the specified separator.