ENH: Allow env to be set for SystemFormulas

Allow env to be changed for system formulas
Add doc string for predict
Test rare predict paths
Test rare formula parser paths

linearmodels/system/model.py

@@ -201,6 +201,22 @@ def formula(self):
         """Cleaned version of formula"""
         return self._clean_formula
 
+    @property
+    def eval_env(self):
+        """Set or get the eval env depth"""
+        return self._eval_env
+
+    @eval_env.setter
+    def eval_env(self, value):
+        self._eval_env = value
+        # Update parsers for new level
+        parsers = self._parsers
+        new_parsers = OrderedDict()
+        for key in parsers:
+            parser = parsers[key]
+            new_parsers[key] = IVFormulaParser(parser._formula, parser._data, self._eval_env)
+        self._parsers = new_parsers
+
     @property
     def equation_labels(self):
         return list(self._parsers.keys())
@@ -532,6 +548,47 @@ def __str__(self):
         return out
 
     def predict(self, params, *, equations=None, data=None, eval_env=8):
+        """
+        Predict values for additional data
+
+        Parameters
+        ----------
+        params : array-like
+            Model parameters (nvar by 1)
+        equations : dict
+            Dictionary-like structure containing exogenous and endogenous
+            variables.  Each key is an equations label and must
+            match the labels used to fir the model. Each value must be either a tuple
+            of the form (exog, endog) or a dictionary with keys 'exog' and 'endog'.
+            If predictions are not required for one of more of the model equations,
+            these keys can be omitted.
+        data : DataFrame
+            Values to use when making predictions from a model constructed
+            from a formula
+        eval_env : int
+            Depth of use when evaluating formulas using Patsy.
+
+        Returns
+        -------
+        predictions : DataFrame
+            Fitted values from supplied data and parameters
+
+        Notes
+        -----
+        If `data` is not none, then `equations` must be none.
+        Predictions from models constructed using formulas can
+        be computed using either `equations`, which will treat these are
+        arrays of values corresponding to the formula-process data, or using
+        `data` which will be processed using the formula used to construct the
+        values corresponding to the original model specification.
+
+        When using `exog` and `endog`, the regressor array for a particular
+        equation is assembled as
+        `[equations[eqn]['exog'], equations[eqn]['endog']]` where `eqn` is
+        an equation label. These must correspond to the columns in the
+        estimated model.
+        """
+
         if data is not None:
             parser = SystemFormulaParser(self.formula, data=data, eval_env=eval_env)
             equations = parser.data
@@ -543,19 +600,22 @@ def predict(self, params, *, equations=None, data=None, eval_env=8):
         for i, label in enumerate(self._eq_labels):
             kx = self._x[i].shape[1]
             if label in equations:
+                b = params[loc:loc + kx]
                 eqn = equations[label]  # type: dict
                 exog = eqn.get('exog', None)
                 endog = eqn.get('endog', None)
                 if exog is None and endog is None:
+                    loc += kx
                     continue
+
                 if exog is not None:
                     exog_endog = IVData(exog).pandas
                     if endog is not None:
                         endog = IVData(endog)
                         exog_endog = concat([exog_endog, endog.pandas], 1)
                 else:
                     exog_endog = IVData(endog).pandas
-                b = params[loc:loc + kx]
+
                 fitted = exog_endog.values @ b
                 fitted = DataFrame(fitted, index=exog_endog.index, columns=[label])
                 out[label] = fitted

linearmodels/tests/panel/test_formula.py

@@ -4,10 +4,12 @@
 import pandas as pd
 import pytest
 
+from linearmodels.compat.pandas import assert_frame_equal
 from linearmodels.formula import (between_ols, first_difference_ols, panel_ols,
                                   pooled_ols, random_effects, fama_macbeth)
 from linearmodels.panel.model import (BetweenOLS, FirstDifferenceOLS, PanelOLS,
-                                      PooledOLS, RandomEffects, FamaMacBeth)
+                                      PooledOLS, RandomEffects, FamaMacBeth,
+                                      PanelFormulaParser)
 from linearmodels.tests.panel._utility import generate_data, datatypes
 
 pytestmark = pytest.mark.filterwarnings('ignore::linearmodels.utility.MissingValueWarning')
@@ -40,6 +42,11 @@ def models(request):
     return request.param
 
 
+@pytest.fixture(params=[True, False])
+def effects(request):
+    return request.param
+
+
 def sigmoid(v):
     return np.exp(v) / (1 + np.exp(v))
 
@@ -216,3 +223,30 @@ def test_formulas_predict_error(data, models, formula):
     res = model(data.y, x[vars]).fit()
     with pytest.raises(ValueError):
         res.predict(data=joined)
+
+
+def test_parser(data, formula, effects):
+    if not isinstance(data.y, pd.DataFrame):
+        return
+    if effects:
+        formula += ' + EntityEffects + TimeEffects'
+    joined = data.x
+    joined['y'] = data.y
+    parser = PanelFormulaParser(formula, joined)
+    dep, exog = parser.data
+    assert_frame_equal(parser.dependent, dep)
+    assert_frame_equal(parser.exog, exog)
+    parser.eval_env = 3
+    assert parser.eval_env == 3
+    parser.eval_env = 2
+    assert parser.eval_env == 2
+    assert parser.entity_effect == ('EntityEffects' in formula)
+    assert parser.time_effect == ('TimeEffects' in formula)
+
+    formula += ' + FixedEffects '
+    if effects:
+        with pytest.raises(ValueError):
+            PanelFormulaParser(formula, joined)
+    else:
+        parser = PanelFormulaParser(formula, joined)
+        assert parser.entity_effect

linearmodels/tests/system/test_formulas.py

@@ -1,3 +1,4 @@
+from collections import OrderedDict
 from itertools import product
 
 import numpy as np
@@ -7,6 +8,7 @@
 from linearmodels import SUR, IVSystemGMM, IV3SLS
 from linearmodels.compat.pandas import assert_series_equal, assert_frame_equal
 from linearmodels.formula import sur, iv_system_gmm, iv_3sls
+from linearmodels.system.model import SystemFormulaParser
 from linearmodels.tests.system._utility import generate_3sls_data_v2
 from linearmodels.utility import AttrDict
 
@@ -100,6 +102,20 @@ def test_predict_partial(config):
     pred2 = res.predict(data=joined, dataframe=True)
     assert_frame_equal(pred2[pred.columns], pred)
 
+    eqns = AttrDict()
+    for key in list(mod._equations.keys())[1:]:
+        eqns[key] = mod._equations[key]
+    final = list(mod._equations.keys())[0]
+    eqns[final] = {'exog': None, 'endog': None}
+    pred3 = res.predict(equations=eqns, dataframe=True)
+    assert_frame_equal(pred2[pred3.columns], pred3)
+
+    eqns = AttrDict()
+    for key in mod._equations:
+        eqns[key] = {k: v for k, v in mod._equations[key].items() if v.shape[1] > 0}
+    pred4 = res.predict(equations=eqns, dataframe=True)
+    assert_frame_equal(pred2, pred4)
+
 
 def test_invalid_predict(config):
     fmla, model, interface = config
@@ -110,3 +126,37 @@ def test_invalid_predict(config):
     res = mod.fit()
     with pytest.raises(ValueError):
         res.predict(data=joined, equations=mod._equations)
+
+
+def test_parser(config):
+    fmla, model, interface = config
+    parser = SystemFormulaParser(fmla, joined, eval_env=5)
+    orig_data = parser.data
+    assert isinstance(orig_data, OrderedDict)
+    assert parser.eval_env == 5
+
+    parser.eval_env = 4
+    assert parser.eval_env == 4
+    exog = parser.exog
+    dep = parser.dependent
+    endog = parser.endog
+    instr = parser.instruments
+    for key in orig_data:
+        eq = orig_data[key]
+        assert_frame_equal(exog[key], eq['exog'])
+        assert_frame_equal(dep[key], eq['dependent'])
+        assert_frame_equal(endog[key], eq['endog'])
+        assert_frame_equal(instr[key], eq['instruments'])
+
+    labels = parser.equation_labels
+    for label in labels:
+        assert label in orig_data
+    new_parser = SystemFormulaParser(parser.formula, joined, eval_env=5)
+
+    new_data = new_parser.data
+    for key in orig_data:
+        eq1 = orig_data[key]
+        eq2 = new_data[key]
+        for key in eq1:
+            if eq1[key] is not None:
+                assert_frame_equal(eq1[key], eq2[key])