Fixes a bug where we'd fail to raise an error if the start/end of a
history window call don't aren't in the loader's calendar.
We were started dropping this error after a previous change swapped out
calls to `index.get_loc` with calls to `index.searchsorted` to avoid
creating hash tables in pandas.
The use of `slice_indexer` on all market minutes was taking about 110ms on my
development machine.
This change to getting the start and end indices changes the entire `_calendar`
method to take 10ms on the same machine.
Noticed while creating a `HistoryLoader` in a notebook context.
In preparation for using `DataPortal` in notebooks, remove restriction on
the `HistoryLoader` to dates that are monotonically increasing. Notebook
usage of the `DataPortal` is more useful when the end of the history
window can be arbitrary dates without having to restart the notebook kernel.
Due to the implementation of the prefetch and caching logic, the end
date of history calls could previously only increase. e.g. `2016-11-01`,
`2016-11-02`, `2016-11-03`. This pattern was sufficient for backtesting
and live simulations, since the current time of the algorithm only ever increases.
With this change, which resets the underlying sliding window when the
last fetched idx is greater than the
Now calls to history in the same process with end dates such
`2016-11-01`, `2016-10-31`, `2015-11-02` should work.
To support using a `DataPortal` and `HistoryLoader` in a notebook, allow
the prefetch length to be configurable, so that it can be set to 0.
Unlike backtesting where the prefetch is useful for repeated history
windows viewed from datetimes which are monotonically increasing by a
small amount, the notebook usage of history windows needs only to
retrieve the exact data needed for the window specified.
This patch also fixes some boundary conditions related to rolls and
adjustments which were uncovered by querying for the adjustments with an
end date near the end of the window.
Instead of using the difference between the session close of the front
contract before the roll and and the open of back contract on the
beginning of the roll, use the close of both at the end of the session
before the roll.
The closes of the session prior to roll is in lieu of settlement data.
There have been cases where the requested start or end date is not in
the history calendar.
Add the beginning and of the calendar to the KeyError to give more
detail to figure out root cause.
If a KeyError occurred in the adjustment logic, the exception would be
swallowed by the try block, which was intended to just check whether or
not there was an adjustment reader adjusted.
Discovered when some logic in a futures adjustment reader were failing
because of a mismatch of minute and session labels, which resulted in no
adjustments during windows when there should have been.
Add `.adj('mul')` and `.adj('add')` methods on ContinuousFuture, which
when used with `history`, will calculate and apply adjustments so that
the values are adjusted to account for discounts and premiums during
rolls.
Example usage in an algo:
```
from zipline.api import continuous_future
def initialize(context):
context.cl_add = continuous_future('CL', offset=0, roll='calendar').adj('add')
context.cl_mul = continuous_future('CL', offset=0, roll='calendar').adj('mul')
context.cl = continuous_future('CL', offset=0, roll='calendar')
schedule_function(print_history)
def print_history(context, data):
frame = data.history([context.cl, context.cl_add, context.cl_mul],
['price', 'sid'],
20,
'1d')
print 'unadjusted'
print frame.loc[:, :, context.cl]
print 'adjusted add'
print frame.loc[:, :, context.cl_add]
print 'adjusted mul'
print frame.loc[:, :, context.cl_mul]
```
Start making the equity adjustments calculations for the history loader
conform to the same method signature as `load_adjustments` provided by
`SQLiteAdjustmentReader, so that an `AdjustmentReader` interface can
begin to take form.
This prepares for creating a `DispatchAdjustmentReader` which will route
adjustment calculations for equities to the
`HistoryCompatibleUSEquityAdjustmentReader` and continuous futures to a
not yet implemented adjustment reader. All of these readers will share
the `load_adjustments` method.
Add a perspective offset to `AdjustedArrayWindow` and `AdjustedArray`,
so that `HistoryLoader` does not need to twiddle with offsets to support
viewing the data from the bar after end of the window, (Which is the
case when a '1d' history window is retrieved in minute mode, which is
explained in the docstring for `HistoryLoader.history`)
Presently, this simplifies the logic in
`HistoryLoader._get_adjustments_in_range`, and other incoming
AdjustmentReader's, (e.g. the roll based adjustment reader for continous
futures.) This patch should also make it easier for history and pipeline
to converge on a singular `load_adjustments` method.
Enable unadjusted history for continuous futures.
The history array is filled by the values for the underlying contracts,
where the contract used changes based on rolls.
e.g., if a `1d` history window was over the range
`2016-01-20` -> `2016-02-29` with contracts with a suffix of `F16` that
rolls at the beginning of the session on `2016-01-26`, `G16` on
`2016-02-26`, and `H16` on `2016-03-26`. The `2016-01-20` ->
`2016-01-25` portion would use the values for `F16', the `2016-01-26` ->
`2016-02-25` portion would use `G16` and the `2016-02-26` ->
`2016-02-29` portion would use `H16`.
Using the same contracts as above, a `1m` history window over the range
(using a timezone of US/Eastern) `2016-01-25 4:00PM` -> `2016-01-25
7:00PM` would fill the `4:00PM` -> `6:00PM` portion with data for `F16`
and the `6:01PM` -> `7:00PM` portion with data for `G16`, since the
beginning of the `2016-01-26` session is `2016-01-25 6:01PM`.
Supports `1d` and `1m`.
Also adds the `sid` field to `history` to assist in showing the active
contract at each dt in the window.
This reverts commit 86c7635b45, reversing
changes made to c77f2b92df.
Some real world cases hit errors with this change, due to the new offset
logic attempting to create Adjustments with invalid parameters.
Will identify exact conditions that cause this error and add as a test
case before remerging.
Instead of `HistoryLoader` containing separate adjustment calculation
logic, use `SQLiteAdjustmentReader.load_adjustments`.
This change required the addition of two offset parameters to
`load_adjustments` since the perspective on the data from within
`schedule_function` is skewed from how Pipeline looks at historical
data.
This is working towards creating an `AdjustmentReader` abc which
`SQLiteAdjustmentReader` and a upcoming continuous future adjustment
reader will share.
Scott Sanderson