Given an iterator of key/value pairs, this iterator will lazily group
items with the same key as a sub-iterator. In terms of types, the
method does the following:
Iterator[(K, V)] => Iterator[(K, Iterator[V])]
Unlike other methods which will require loading much or all of the
initial iterator into memory, this method only maintains one item
worth of state (to "look ahead" and see what is coming next).
The most obvious use of this method for grouping data that has already
been sorted. The expectation is that this will be useful to go between
Scalding and Spark.
non
commented
5 years ago
Given an iterator of key/value pairs, this iterator will lazily group items with the same key as a sub-iterator. In terms of types, the method does the following:
Unlike other methods which will require loading much or all of the initial iterator into memory, this method only maintains one item worth of state (to "look ahead" and see what is coming next).
The most obvious use of this method for grouping data that has already been sorted. The expectation is that this will be useful to go between Scalding and Spark.