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DOC: update docstrings for lookup_*symbol

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This commit is contained in:
Joe Jevnik
2016-06-24 20:45:26 -04:00
parent fb532c3fe8
commit d7620b7063
1 changed files with 42 additions and 18 deletions
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zipline/assets/assets.py
+42 -18
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@@ -548,13 +548,12 @@ class AssetFinder(object):
# we have an entry but it is empty
raise KeyError('goto error')
except KeyError:
# no one has ever held this symbol
# no equity has ever held this symbol
raise SymbolNotFound(symbol=symbol)
if not as_of_date:
if len(owners) > 1:
# more than one equity has held this ticker, this is ambiguous
# more than one equity has held this ticker, this is ambigious
# without the date
raise MultipleSymbolsFound(
symbol=symbol,
@@ -564,16 +563,16 @@ class AssetFinder(object):
)),
)
# exactly one company has ever held this symbol, we may resolve
# exactly one equity has ever held this symbol, we may resolve
# without the date
return self.retrieve_asset(owners[0].sid)
for start, end, sid, _ in owners:
if start <= as_of_date < end:
# find the company that owned it on the given asof date
# find the equity that owned it on the given asof date
return self.retrieve_asset(sid)
# no company held the ticker on the given asof date
# no equity held the ticker on the given asof date
raise SymbolNotFound(symbol=symbol)
def _lookup_symbol_fuzzy(self, symbol, as_of_date):
@@ -587,12 +586,12 @@ class AssetFinder(object):
# we have an entry but it is empty
raise KeyError('goto error')
except KeyError:
# no one has ever held a symbol matching the fuzzy symbol
# no equity has ever held a symbol matching the fuzzy symbol
raise SymbolNotFound(symbol=symbol)
if not as_of_date:
if not owners:
# no one held the fuzzy symbol ever
# no equity held the fuzzy symbol ever
raise SymbolNotFound(symbol=symbol)
if len(owners) == 1:
@@ -622,7 +621,7 @@ class AssetFinder(object):
options.append((sid, sym))
if not options:
# no one owned the fuzzy symbol on the date requested
# no equity owned the fuzzy symbol on the date requested
SymbolNotFound(symbol=symbol)
if len(options) == 1:
@@ -634,7 +633,7 @@ class AssetFinder(object):
# look for an exact match on the asof date
return self.retrieve_asset(sid)
# multiple companies held tickers matching the fuzzy ticker but
# multiple equities held tickers matching the fuzzy ticker but
# there are no exact matches
raise MultipleSymbolsFound(
symbol=symbol,
@@ -645,20 +644,45 @@ class AssetFinder(object):
)
def lookup_symbol(self, symbol, as_of_date, fuzzy=False):
"""
Return matching Equity of name symbol in database.
"""Lookup an equity by symbol.
If multiple Equities are found and as_of_date is not set,
raises MultipleSymbolsFound.
Parameters
----------
symbol : str
The ticker symbol to resolve.
as_of_date : datetime or None
Look up the last owner of this symbol as of this datetime.
If ``as_of_date`` is None, then this can only resolve the equity
if exactly one equity has ever owned the ticker.
fuzzy : bool, optional
Should fuzzy symbol matching be used? Fuzzy symbol matching
attempts to resolve differences in representations for
shareclasses. For example, some people may represent the ``A``
shareclass of ``BRK`` as ``BRK.A``, where others could write
``BRK_A``.
If no Equity was active at as_of_date raises SymbolNotFound.
Returns
-------
equity : Equity
The equity that held ``symbol`` on the given ``as_of_date``, or the
only equity to hold ``symbol`` if ``as_of_date`` is None.
Raises
------
SymbolNotFound
Raised when no equity has ever held the given symbol.
MultipleSymbolsFound
Raised when no ``as_of_date`` is given and more than one equity
has held ``symbol``. This is also raised when ``fuzzy=True`` and
there are multiple candidates for the given ``symbol`` on the
``as_of_date``.
"""
if fuzzy:
return self._lookup_symbol_fuzzy(symbol, as_of_date)
return self._lookup_symbol_strict(symbol, as_of_date)
def lookup_future_symbol(self, symbol):
""" Return the Future object for a given symbol.
"""Lookup a future contract by symbol.
Parameters
----------
@@ -667,8 +691,8 @@ class AssetFinder(object):
Returns
-------
Future
A Future object.
future : Future
The future contract referenced by ``symbol``.
Raises
------