def empirical_ema_r1(y: Y_TYPE,
s,
k: int,
a: A_TYPE = None,
t: T_TYPE = None,
e: E_TYPE = None,
r: R_TYPE = None):
""" Exponential moving average, with empirical std
r weight to place on existing anchor point
"""
assert r is not None
y0 = wrap(y)[0]
if not s.get('p'):
s = {'p': {}, 'x': y0, 'rho': r}
assert 0 <= s['rho'] <= 1, 'Expecting rho=r to be between 0 and 1'
else:
assert abs(r - s['rho']) < 1e-6, 'rho=r is immutable'
if y0 is None:
return None, s, None
else:
s['x'] = s['rho'] * s['x'] + (1 - s['rho']) * y0 # Make me better !
x = [s['x']] * k
_we_ignore_bias, x_std, s['p'] = parade(p=s['p'], x=x, y=y0)
x_std_fallback = nonecast(x_std, fill_value=1.0)
return [s['x']] * k, x_std_fallback, s
def regress_level_on_first_known(y:Y_TYPE, s:dict, k, a:A_TYPE=None, t:T_TYPE =None, e:E_TYPE =None)->([float] , Any , Any):
""" Very basic online regression skater, mostly for testing
- Only one known in advance variable is utilized
- Last value is ignored, unless a is None in which case we return 0.0
- Empirical std is returned
"""
y0 = wrap(y)[0] # Ignore contemporaneous, exogenous variables
if a:
a0 = wrap(a)[0] # Ignore all but the first known-in-advance variable
if not s.get('k'):
# First invocation
s = {'p': {}} # Prediction parade
s['r'] = {} # Regression state, not to be confused with hyper-param r
s['k'] = k
s['o'] = {} # The "observance" will quarantine 'a' until it can be matched
else:
assert s['k']==k # Immutability
if a is None:
return [0]*k, [1.0]*k, s
else:
a_t, s['o'] = observance( y=[y0],o=s['o'], k=k, a= [a0]) # Update the observance
if a_t is not None: # This is the contemporaneous 'a', which was supplied k calls ago.
if not s['r']:
# When first calling the online regression algorithm we avoid the degenerate case
# by sending it two observations.
y_noise = 0.1*(1e-6+abs(y0))*np.random.randn()
x_noise = 0.1*(1e-6+abs(a0))*np.random.randn()
x = [ a_t[0]-x_noise, a_t[0]+x_noise ]
y = [ y0-y_noise, y0+y_noise ]
s['r'] = regress_one_helper(x=x, y=y, r=s['r'])
else:
s['r'] = regress_one_helper(x=a_t, y=[y0], r=s['r'])
# Predict using contemporaneous alpha's
x = [ s['r']['alpha'] + s['r']['beta']*ak[0] for ak in s['o']['a'] ]
# Push prediction into the parade and get the current bias/stderr
bias, x_std, s['p'] = parade(p=s['p'], x=x, y=y0)
return x, x_std, s # TODO: Use the std implied by regression instead
else:
x = [y0]*k
bias, x_std, s['p'] = parade(p=s['p'], x=x, y=y0)
return x , x_std, s
def tsa_factory(y: Y_TYPE,
s: dict,
k: int,
a: A_TYPE = None,
t: T_TYPE = None,
e: E_TYPE = None,
p: int = TSA_P_DEFAULT,
d: int = TSA_D_DEFAULT,
q: int = TSA_D_DEFAULT) -> ([float], Any, Any):
""" Extremely simple univariate, fixed p,d,q ARIMA model that is re-fit each time """
# TODO: FIX THIS TO USE EMPIRICAL STD, OTHERWISE ENSEMBLES ARE DREADFUL
y = wrap(y)
a = wrap(a)
if not s.get('y'):
s = {'y': list(), 'a': list(), 'k': k, 'p': {}}
else:
# Assert immutability of k, dimensions
if s['y']:
assert len(y) == len(s['y'][0])
assert k == s['k']
if s['a']:
assert len(a) == len(s['a'][0])
if y is None:
return None, s, None
else:
s['y'].append(y)
if a is not None:
s['a'].append(a)
if len(s['y']) > max(2 * k + 5, TSA_META['n_warm']):
y0s = [y_[0] for y_ in s['y']]
model = ARIMA(y0s, order=(p, d, q))
try:
x = list(model.fit().forecast(steps=k))
except:
x = [wrap(y)[0]] * k
else:
x = [y[0]] * k
y0 = wrap(y)[0]
_we_ignore_bias, x_std, s['p'] = parade(p=s['p'], x=x, y=y0)
x_std_fallback = nonecast(x_std, fill_value=1.0)
return x, x_std_fallback, s
def empirical_last_value(y: Y_TYPE,
s: dict,
k: int = 1,
a: A_TYPE = None,
t: T_TYPE = None,
e: E_TYPE = None) -> ([float], Any, Any):
""" Last value cache, with empirical std """
if not s.get('p'):
s = {'p': {}} # Initialize prediction parade
if y is None:
return None, None, s
else:
y0 = wrap(y)[0] # Ignore the rest
x = [y0] * k # What a great prediction !
bias, x_std, s['p'] = parade(p=s['p'], x=x,
y=y0) # update residual queue
return x, x_std, s
def fbprophet_skater_factory(y: Y_TYPE, s: dict, k: int, a: A_TYPE = None,
t: T_TYPE = None, e: E_TYPE = None,
emp_mass: float = 0.0, emp_std_mass: float = 0.0,
freq=None, recursive: bool = False,
model_params: dict = None,
n_max: int = None) -> ([float], Any, Any):
""" Prophet skater with running prediction error moments
Hyper-parameters are explicit here, whereas they are determined from r in actual skaters.
Params of note:
a: value of known-in-advance vars k step in advance (not contemporaneous with y)
"""
assert 0 <= emp_mass <= 1
assert 0 <= emp_std_mass <= 1
if freq is None:
freq = PROPHET_META['freq']
if n_max is None:
n_max = PROPHET_META['n_max']
y = wrap(y)
a = wrap(a)
if not s.get('y'):
s = {'p': {}, # parade
'y': list(), # historical y
'a': list(), # list of a known k steps in advance
't': list(),
'k': k}
else:
# Assert immutability of k, dimensions of y,a
if s['y']:
assert len(y) == len(s['y'][0])
assert k == s['k']
if s['a']:
assert len(a) == len(s['a'][0])
if y is None:
return None, s, None
else:
s['y'].append(y)
if a is not None:
s['a'].append(a)
if t is not None:
assert isinstance(t,float), 'epoch time please'
s['t'].append(t)
if len(s['y']) > max(2 * k + 5, PROPHET_META['n_warm']):
# Offset y, t, a are supplied to prophet interface
t_arg = s['t'][k:] if t is not None else None
a_arg = s['a']
y_arg = s['y'][k:]
x, x_std, forecast, model = prophet_iskater_factory(y=y_arg, k=k, a=a_arg, t=t_arg,
freq=freq, n_max=n_max,
recursive=recursive, model_params=model_params)
s['m'] = True # Flag indicating a model has been fit (there is no point keeping the model itself, however)
else:
x = [y[0]] * k
x_std = None
# Get running mean prediction errors from the prediction parade
x_resid, x_resid_std, s['p'] = parade(p=s['p'], x=x, y=y[0])
x_resid = nonecast(x_resid,y[0])
x_resid_std = nonecast(x_resid_std,1.0)
# Compute center of mass between bias-corrected and uncorrected predictions
x_corrected = np.array(x_resid) + np.array(x)
x_center = nonecenter(m=[emp_mass, 1 - emp_mass], x=[x_corrected, x])
x_std_center = nonecenter(m=[emp_std_mass, 1 - emp_std_mass], x=[x_resid_std, x_std])
return x_center, x_std_center, s
