Adds a new ``downsample`` method to all computable terms. Computable
terms (Filters, Factors, and Classifiers) can be downsampled to yearly,
quarterly, monthly, or weekly frequency.
The result of ``term.downsample`` is a new term of the same
family (Filter/Factor/Classifier) as ``term``. The downsampled term
computes by delegating to the original term; repeatedly calling its
``compute`` method with length-1 date ranges.
Downsampled terms take advantage of a new ``compute_extra_rows`` Term
method, which allows terms to dynamically request that additional extra
rows of themselves be computed based on the dates for which they're
being computed. This ensures, for example, that a monthly-downsampled
term always computes at the start of a month, even when a
naively-calculated pipeline window would end in the middle of the month.
- Split out extra_rows handling into an `ExecutionPlan` subclass.
`ExecutionPlan` now requires the dates and calendar against which a
set of terms will be computed, and now defers to a term's
`compute_extra_rows` method when deciding how many extra rows are
required to compute for that term. This will allow downsampled terms
to request enough extra rows to guarantee that we can maintain consistent
calculation dates.
As a consequence of the above, `TermGraph` now only deals with logical
dependencies, not with metadata surrounding extra row calculations.
This means that TermGraph can be used to generate dependency
visualizations in interactive contexts where we don't yet have a
calendar or start/end dates.
- Refactored test_{filter,factor,classifier} to use check_terms instead
of run_graph. This makes it easier to make changes to TermGraph,
since the testing interface is now to simply provide a dict of terms.
- Refactored BasePipelineTestCase to use fixtures to create an asset
finder. This fixes a potential leak of the test's asset db, which was
not being explicitly cleaned up.
- Refactored test_technical to use BasePipelineTestCase.
- Added a new special term, `InputDates()`, which can be used to request
date labels for inputs. Like `AssetExists`, `InputDates` is provided
in the initial workspace by default.
- Added a default (failing) `_compute` method to `AssetExists` which
provides a more useful error than AttributeError.
* BUG: Fixes asset writer to the select the latest asset to hold a sid
When constructing the asset_info dataframe, we were previously taking
the first symbol/sid pair to include, when we should be taking the most
recent.
* Ensure groups are sorted by increasing end_date
* Updates test_lookup_symbol_change_ticker to also cover asset_name
- Don't create unnecessary extra data (requires passing fastd_period=1
to TA-Lib or else it fills the FastK with NaNs even though it must
have already computed them...
- Use random_sample instead of random_integers so that we're not
dependent on integer arithmetic.
- Pass array_decimal to assert_equal so that we do almost equal checking
on results.
Use the future asset equity pricing reader, instead of reading directly
from the bcolz table. Required since the format for writing the future
data now uses the minute bar reader/writer pair.
Add test cases to `test_data_portal` asserting both equity and future
`get_spot_value` results.
Scott Sanderson