AMDG Eric Niebler <eric <at> boost-consulting.com> writes:
It's not exactly what you're asking for, but if you want to modify a time_series in-place, you can do that with range_run_storage::set_at(). It's a terrible way to build a series though, because you need to find the place in the series where this element should be inserted (could be O(log N)) and then insert it (could be O(N)).
You seem to be asking for an ordered_append feature. That might be useful to add.
Is there some reason why this doesn't work? If I need the other behavior I can always create a new series fill it and swap myself.
Fill it how? That's exactly what ordered_inserter is for! So you can see, ordered_inserter is necessary. But the name isn't right.
I would fill it using ordered_append.
The reason for ordered_inserter's existence is that it is the fastest way to build a time_series from scratch, regardless of the internal representation. When you know elements are sorted, you can just bang them into a dense vector, sparse vector, map, or what-have-you -- very efficient. Once you have a time series, there are other ways to manipulate it.
The reason for .commit() is that, since you're pushing in one datum at a time, there may be a more efficient intermediate representation than the final time series data structure. For the scenarios I've encountered, being able to efficiently build a series by pushing in one datum at a time is important.
Do you have an example where pushing them using a different intermediate representation is significantly more efficient? Even if there is such a case should we really use an interface for insertion that departs from established practice even when it isn't needed? Would it be possible to have a range assign function template in addition to the inserter that takes a sequence of tuples? Could this be as efficient as the current ordered inserter?
The alternative would be use a range-based interface like the STL uses. E.g.:
series.assign( from, to );
Here, "from" and "to" can't really be iterators though, or, if they are, they should yield a 3-tuple of (value, offset, end offset). An interface like this is very unwieldy in signal processing, where you often collect data by polling a value at an interval.
for(;;) series.push_back(poll_some_value(), last_time, current_time);
Of course, push_back() may not be the most efficient way to build up some kinds of data structures. What the ordered_inserter gives is a way have something as efficient as a range-based assign() while retaining the poll-and-push-back convenience.
Does that make sense?
No. std::vector<tuple<...> > elements; for(;;) elements.push_back(make_tuple(poll_some_value(), last_time, current_time)); series.assign(elements); vs. ordered_inserter inserter(series); for(;;) *insert++ = make_tuple(poll_some_value(), last_time, current_time); inserter.commit(); In Christ, Steven Watanabe