def _estimate_svar(self,
start_params,
lags,
maxiter,
maxfun,
trend='c',
solver="nm",
override=False):
"""
lags : int
trend : string or None
As per above
"""
k_trend = util.get_trendorder(trend)
y = self.endog
z = util.get_var_endog(y, lags, trend=trend, has_constant='raise')
y_sample = y[lags:]
# Lutkepohl p75, about 5x faster than stated formula
var_params = np.linalg.lstsq(z, y_sample, rcond=-1)[0]
resid = y_sample - np.dot(z, var_params)
# Unbiased estimate of covariance matrix $\Sigma_u$ of the white noise
# process $u$
# equivalent definition
# .. math:: \frac{1}{T - Kp - 1} Y^\prime (I_T - Z (Z^\prime Z)^{-1}
# Z^\prime) Y
# Ref: Lutkepohl p.75
# df_resid right now is T - Kp - 1, which is a suggested correction
avobs = len(y_sample)
df_resid = avobs - (self.neqs * lags + k_trend)
sse = np.dot(resid.T, resid)
#TODO: should give users the option to use a dof correction or not
omega = sse / df_resid
self.sigma_u = omega
A, B = self._solve_AB(start_params,
override=override,
solver=solver,
maxiter=maxiter,
maxfun=maxfun)
A_mask = self.A_mask
B_mask = self.B_mask
return SVARResults(y,
z,
var_params,
omega,
lags,
names=self.endog_names,
trend=trend,
dates=self.data.dates,
model=self,
A=A,
B=B,
A_mask=A_mask,
B_mask=B_mask)
def format_data_for_estimate_var(endog_list, exog_list, lag):
k_trend = 1
explanatory_data = []
target_data = []
for i in range(len(endog_list)):
endog = endog_list[i]
exog = None
if len(exog_list) > 0:
exog = exog_list[i]
nobs = len(endog) - lag
if exog is not None and len(endog) != len(exog):
raise ValueError(
"Endog has length {} but exog has length {} - i={}".format(
len(endog), len(exog), i))
if nobs <= 0:
raise ValueError(
"Endog only has {} observations but requesting with {} lags - i={}"
.format(len(endog), lag, i))
useful_endog = endog[-nobs - lag:]
z = util.get_var_endog(useful_endog, lag, has_constant='raise')
if exog is not None:
useful_exog = exog[-nobs:]
x = util.get_var_endog(useful_exog,
0,
trend='nc',
has_constant='raise')
x = np.column_stack((x, useful_exog))
temp_z = z
z = np.empty((x.shape[0], x.shape[1] + z.shape[1]))
z[:, :k_trend] = temp_z[:, :k_trend]
z[:, k_trend:k_trend + x.shape[1]] = x
z[:, k_trend + x.shape[1]:] = temp_z[:, k_trend:]
for i in range(k_trend):
if (np.diff(z[:, i]) == 1).all(): # modify the trend-column
z[:, i] += lag
# make the same adjustment for the quadratic term
if (np.diff(np.sqrt(z[:, i])) == 1).all():
z[:, i] = (np.sqrt(z[:, i]) + lag)**2
explanatory_data.extend(z)
target_data.extend(endog[-nobs:])
return target_data, explanatory_data
def _estimate_svar(self, start_params, lags, maxiter, maxfun, trend="c", solver="nm", override=False):
"""
lags : int
trend : string or None
As per above
"""
k_trend = util.get_trendorder(trend)
y = self.endog
z = util.get_var_endog(y, lags, trend=trend)
y_sample = y[lags:]
# Lutkepohl p75, about 5x faster than stated formula
var_params = np.linalg.lstsq(z, y_sample)[0]
resid = y_sample - np.dot(z, var_params)
# Unbiased estimate of covariance matrix $\Sigma_u$ of the white noise
# process $u$
# equivalent definition
# .. math:: \frac{1}{T - Kp - 1} Y^\prime (I_T - Z (Z^\prime Z)^{-1}
# Z^\prime) Y
# Ref: Lutkepohl p.75
# df_resid right now is T - Kp - 1, which is a suggested correction
avobs = len(y_sample)
df_resid = avobs - (self.neqs * lags + k_trend)
sse = np.dot(resid.T, resid)
# TODO: should give users the option to use a dof correction or not
omega = sse / df_resid
self.sigma_u = omega
A, B = self._solve_AB(start_params, override=override, solver=solver, maxiter=maxiter, maxfun=maxfun)
A_mask = self.A_mask
B_mask = self.B_mask
return SVARResults(
y,
z,
var_params,
omega,
lags,
names=self.endog_names,
trend=trend,
dates=self.data.dates,
model=self,
A=A,
B=B,
A_mask=A_mask,
B_mask=B_mask,
)
def _estimate_var(self, lags, offset=0, trend="c"):
"""
lags : int
offset : int
Periods to drop from beginning-- for order selection so it's an
apples-to-apples comparison
trend : string or None
As per above
"""
# have to do this again because select_order doesn't call fit
self.k_trend = k_trend = util.get_trendorder(trend)
if offset < 0: # pragma: no cover
raise ValueError("offset must be >= 0")
y = self.y[offset:]
z = util.get_var_endog(y, lags, trend=trend)
y_sample = y[lags:]
# Lutkepohl p75, about 5x faster than stated formula
params = np.linalg.lstsq(z, y_sample)[0]
resid = y_sample - np.dot(z, params)
# Unbiased estimate of covariance matrix $\Sigma_u$ of the white noise
# process $u$
# equivalent definition
# .. math:: \frac{1}{T - Kp - 1} Y^\prime (I_T - Z (Z^\prime Z)^{-1}
# Z^\prime) Y
# Ref: Lutkepohl p.75
# df_resid right now is T - Kp - 1, which is a suggested correction
avobs = len(y_sample)
df_resid = avobs - (self.neqs * lags + k_trend)
sse = np.dot(resid.T, resid)
omega = sse / df_resid
varfit = VARResults(
y, z, params, omega, lags, names=self.endog_names, trend=trend, dates=self.data.dates, model=self
)
return VARResultsWrapper(varfit)
def _estimate_var(self, lags, offset=0, trend='c'):
"""
lags : int
offset : int
Periods to drop from beginning-- for order selection so it's an
apples-to-apples comparison
trend : string or None
As per above
"""
# have to do this again because select_order doesn't call fit
self.k_trend = k_trend = util.get_trendorder(trend)
if offset < 0: # pragma: no cover
raise ValueError('offset must be >= 0')
y = self.y[offset:]
z = util.get_var_endog(y, lags, trend=trend)
y_sample = y[lags:]
# Lutkepohl p75, about 5x faster than stated formula
params = np.linalg.lstsq(z, y_sample)[0]
resid = y_sample - np.dot(z, params)
# Unbiased estimate of covariance matrix $\Sigma_u$ of the white noise
# process $u$
# equivalent definition
# .. math:: \frac{1}{T - Kp - 1} Y^\prime (I_T - Z (Z^\prime Z)^{-1}
# Z^\prime) Y
# Ref: Lutkepohl p.75
# df_resid right now is T - Kp - 1, which is a suggested correction
avobs = len(y_sample)
df_resid = avobs - (self.neqs * lags + k_trend)
sse = np.dot(resid.T, resid)
omega = sse / df_resid
varfit = VARResults(y, z, params, omega, lags, names=self.endog_names,
trend=trend, dates=self.data.dates, model=self)
return VARResultsWrapper(varfit)
def predict(self, params, start=None, end=None, lags=1, trend='c'):
"""
Returns in-sample predictions or forecasts
"""
if start is None:
start = k_ar
# Handle start, end
start, end, out_of_sample, prediction_index = (
self._get_prediction_index(start, end))
if end < start:
raise ValueError("end is before start")
if end == start + out_of_sample:
return np.array([])
k_trend = util.get_trendorder(trend)
k = self.neqs
k_ar = lags
predictedvalues = np.zeros((end + 1 - start + out_of_sample, k))
if k_trend != 0:
intercept = params[:k_trend]
predictedvalues += intercept
y = self.y
X = util.get_var_endog(y, lags, trend=trend, has_constant='raise')
fittedvalues = np.dot(X, params)
fv_start = start - k_ar
pv_end = min(len(predictedvalues), len(fittedvalues) - fv_start)
fv_end = min(len(fittedvalues), end-k_ar+1)
predictedvalues[:pv_end] = fittedvalues[fv_start:fv_end]
if not out_of_sample:
return predictedvalues
# fit out of sample
y = y[-k_ar:]
coefs = params[k_trend:].reshape((k_ar, k, k)).swapaxes(1,2)
predictedvalues[pv_end:] = forecast(y, coefs, intercept, out_of_sample)
return predictedvalues
def predict(self, params, start=None, end=None, lags=1, trend='c'):
"""
Returns in-sample predictions or forecasts
"""
if start is None:
start = k_ar
# Handle start, end
start, end, out_of_sample, prediction_index = (
self._get_prediction_index(start, end))
if end < start:
raise ValueError("end is before start")
if end == start + out_of_sample:
return np.array([])
k_trend = util.get_trendorder(trend)
k = self.neqs
k_ar = lags
predictedvalues = np.zeros((end + 1 - start + out_of_sample, k))
if k_trend != 0:
intercept = params[:k_trend]
predictedvalues += intercept
y = self.y
X = util.get_var_endog(y, lags, trend=trend, has_constant='raise')
fittedvalues = np.dot(X, params)
fv_start = start - k_ar
pv_end = min(len(predictedvalues), len(fittedvalues) - fv_start)
fv_end = min(len(fittedvalues), end-k_ar+1)
predictedvalues[:pv_end] = fittedvalues[fv_start:fv_end]
if not out_of_sample:
return predictedvalues
# fit out of sample
y = y[-k_ar:]
coefs = params[k_trend:].reshape((k_ar, k, k)).swapaxes(1,2)
predictedvalues[pv_end:] = forecast(y, coefs, intercept, out_of_sample)
return predictedvalues
def _estimate_var(self, lags, offset=0, trend='c'):
"""
lags : int
Lags of the endogenous variable.
offset : int
Periods to drop from beginning-- for order selection so it's an
apples-to-apples comparison
trend : string or None
As per above
"""
# have to do this again because select_order doesn't call fit
self.k_trend = k_trend = util.get_trendorder(trend)
if offset < 0: # pragma: no cover
raise ValueError('offset must be >= 0')
nobs = self.n_totobs - lags - offset
endog = self.endog[offset:]
exog = None if self.exog is None else self.exog[offset:]
z = util.get_var_endog(endog, lags, trend=trend, has_constant='raise')
if exog is not None:
# TODO: currently only deterministic terms supported (exoglags==0)
# and since exoglags==0, x will be an array of size 0.
x = util.get_var_endog(exog[-nobs:],
0,
trend="nc",
has_constant="raise")
x_inst = exog[-nobs:]
x = np.column_stack((x, x_inst))
del x_inst # free memory
temp_z = z
z = np.empty((x.shape[0], x.shape[1] + z.shape[1]))
z[:, :self.k_trend] = temp_z[:, :self.k_trend]
z[:, self.k_trend:self.k_trend + x.shape[1]] = x
z[:, self.k_trend + x.shape[1]:] = temp_z[:, self.k_trend:]
del temp_z, x # free memory
# the following modification of z is necessary to get the same results
# as JMulTi for the constant-term-parameter...
for i in range(self.k_trend):
if (np.diff(z[:, i]) == 1).all(): # modify the trend-column
z[:, i] += lags
# make the same adjustment for the quadratic term
if (np.diff(np.sqrt(z[:, i])) == 1).all():
z[:, i] = (np.sqrt(z[:, i]) + lags)**2
y_sample = endog[lags:]
#################################################################################
### TOPOLOGY CONSTRAINED VAR MODEL FITTING
### retrieve sizes associated with coefficient matrix c
num_rows = z.shape[1]
num_nodes = y_sample.shape[1]
### the loss function to minimize difference between [Z]*[C] and [Y], element-wise square-sum of [Z]*[C]-[Y]
def loss(c):
c = c.reshape(
(num_rows, num_nodes)) #convert c from 1D array to 2D
return np.sum(np.square((np.dot(z, c) - y_sample)))
### initial value of variable
c0 = np.zeros((num_rows, num_nodes))
### bounds of variables to be optimized
if self.bounds is not None:
bnds = np.tensordot(np.ones(num_rows * num_nodes),
self.bounds,
axes=0)
else:
bnds = None
### if topology is used as constraints
if self.adjacency is not None:
### Index matrix (with the same size of c) to identify the zero coefficients corresponding to no-connection in graph
## H = np.ones((1,num_nodes),dtype=int) # First row of coefficient (bias) should be zero
H = np.zeros((1, num_nodes), dtype=int)
for i in range(0, lags):
H = np.append(H, (1 - self.adjacency.T), axis=0)
### constraints:
### based on adjacency matrix, non-adjacent coefficients indicated by H are zeros
cons = ({
'type':
'eq',
'fun':
lambda c: np.sum(
np.square(H * c.reshape((num_rows, num_nodes))))
})
if self.adjacency.all(
): ## if with full connections, no constraint should be imposed
res = minimize(loss,
c0,
method='SLSQP',
constraints=(),
bounds=bnds,
options={'disp': True})
else:
res = minimize(loss,
c0,
method='SLSQP',
constraints=cons,
bounds=bnds,
options={'disp': True})
### only Coefficients VALUE RANGE CONSTRAINED VAR MODEL FITTING
else:
## H = np.ones((1,num_nodes),dtype=int) # First row of coefficient (bias) should be zero
## for i in range(0,lags):
## H=np.append(H, np.zeros((num_nodes,num_nodes)), axis=0)
## cons = ({'type': 'eq',
## 'fun' : lambda c: np.sum(np.square(H*c.reshape((num_rows, num_nodes)))) })
res = minimize(loss,
c0,
method='SLSQP',
constraints=(),
bounds=bnds,
options={'disp': True})
params = res.x.reshape((num_rows, num_nodes))
###
###################################################################################
# L�tkepohl p75, about 5x faster than stated formula
# params = np.linalg.lstsq(z, y_sample, rcond=1e-15)[0]
resid = y_sample - np.dot(z, params)
# Unbiased estimate of covariance matrix $\Sigma_u$ of the white noise
# process $u$
# equivalent definition
# .. math:: \frac{1}{T - Kp - 1} Y^\prime (I_T - Z (Z^\prime Z)^{-1}
# Z^\prime) Y
# Ref: L�tkepohl p.75
# df_resid right now is T - Kp - 1, which is a suggested correction
avobs = len(y_sample)
if exog is not None:
k_trend += exog.shape[1]
df_resid = avobs - (self.neqs * lags + k_trend)
sse = np.dot(resid.T, resid)
omega = sse / df_resid
varfit = VARResults(endog,
z,
params,
omega,
lags,
names=self.endog_names,
trend=trend,
dates=self.data.dates,
model=self,
exog=self.exog)
return VARResultsWrapper(varfit)
exog = np.hstack(exog)
var_model = VAR(data, exog)
k_trend = util.get_trendorder('c')
n_totobs = len(data)
p = 1
maxlags = 5
n_totobs = len(data)
lags = p
offset = maxlags + 1 - p
nobs = n_totobs - lags - offset
data = data[offset:]
exog = exog[offset:]
print(data)
Z = np.array([data[t-lags : t][::-1].ravel() for t in range(lags, len(data))])
print(Z)
z = util.get_var_endog(data, lags, trend='c', has_constant='raise')
print(z.shape)
exit()
x = util.get_var_endog(exog[-nobs:], 0, trend="nc", has_constant="raise")
x_inst = exog[-nobs:]
x = np.column_stack((x, x_inst))
temp_z = z
z = np.empty((x.shape[0], x.shape[1]+z.shape[1]))
z[:, :k_trend] = temp_z[:, :k_trend]
z[:, k_trend:k_trend+x.shape[1]] = x
z[:, k_trend+x.shape[1]:] = temp_z[:, k_trend:]
y_sample = data[lags:]
params = np.linalg.lstsq(z, y_sample, rcond=1e-15)[0]
print(z.shape)
