Added routines for dealing with extraction of a single equation from JSON output.

matlab/get_lhs_and_rhs.m

+function [lhs, rhs] = get_lhs_and_rhs(eqname, DynareModel, original)
+
+% Returns the left and right handsides of an equation.
+%
+% INPUTS
+% - lhs         [string]            Left hand side of the equation.
+% - rhs         [string]            Right hand side of the equation.
+% - DynareModel [struct]            Structure describing the current model (M_).
+%
+% OUTPUTS
+% - eqname      [string]            Name of the equation.
+%
+% SPECIAL REQUIREMENTS
+%  The user must have attached names to the equations using equation
+%  tags. Each equation in the model block must be preceeded with a
+%  tag (see the reference manual). For instance, we should have
+%  something as:
+%
+%      [name='Phillips curve']
+%      pi = beta*pi(1) + slope*y + lam;
+
+% Copyright (C) 2018 Dynare Team
+%
+% This file is part of Dynare.
+%
+% Dynare is free software: you can redistribute it and/or modify
+% it under the terms of the GNU General Public License as published by
+% the Free Software Foundation, either version 3 of the License, or
+% (at your option) any later version.
+%
+% Dynare is distributed in the hope that it will be useful,
+% but WITHOUT ANY WARRANTY; without even the implied warranty of
+% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+% GNU General Public License for more details.
+%
+% You should have received a copy of the GNU General Public License
+% along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
+
+if nargin<3
+    original = false;
+end
+
+% Get the equation from the JSON output.
+if original
+    jsonfil = loadjson([DynareModel.fname '_original.json']);
+else
+    jsonfil = loadjson([DynareModel.fname '.json']);
+end
+jsonmod = jsonfil.model;
+jsoneqn = getEquationsByTags(jsonmod, 'name', eqname);
+
+% Get the lhs and rhs members of the selected equation.
+lhs = jsoneqn{1}.lhs;
+rhs = jsoneqn{1}.rhs;
\ No newline at end of file

matlab/get_variables_and_parameters_in_equation.m

+function [pnames, enames, xnames, pid, eid, xid] = get_variables_and_parameters_in_equation(lhs, rhs, DynareModel)
+
+% Returns the lists of parameters, endogenous variables and exogenous variables in an equation.
+%
+% INPUTS
+% - lhs         [string]            Left hand side of an equation.
+% - rhs         [string]            Right hand side of an equation.
+% - DynareModel [struct]            Structure describing the current model (M_).
+%
+% OUTPUTS
+% - pnames      [cell]              Cell of row char arrays (p elements), names of the parameters. 
+% - enames      [cell]              Cell of row char arrays (n elements), names of the endogenous variables.
+% - xnames      [cell]              Cell of row char arrays (m elements), names of the exogenous variables.
+% - pid         [Integer]           p*1 vector of indices in M_.param_names for the listed parameters in params.
+% - eid         [Integer]           n*1 vector of indices in M_.endo_names for the listed parameters in endogenous.
+% - xid         [Integer]           m*1 vector of indices in M_.exo_names for the listed parameters in exogenous.
+
+% Copyright (C) 2018 Dynare Team
+%
+% This file is part of Dynare.
+%
+% Dynare is free software: you can redistribute it and/or modify
+% it under the terms of the GNU General Public License as published by
+% the Free Software Foundation, either version 3 of the License, or
+% (at your option) any later version.
+%
+% Dynare is distributed in the hope that it will be useful,
+% but WITHOUT ANY WARRANTY; without even the implied warranty of
+% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+% GNU General Public License for more details.
+%
+% You should have received a copy of the GNU General Public License
+% along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
+
+% Get the tokens in the rhs member of the equation.
+rhs_ = strsplit(rhs,{'+','-','*','/','^', ...
+                    'log(', 'log10(', 'ln(', 'exp(', ...
+                    'sqrt(', 'abs(', 'sign(', ...
+                    'sin(', 'cos(', 'tan(', 'asin(', 'acos(', 'atan(', ...
+                    'min(', 'max(', ...
+                    'normcdf(', 'normpdf(', 'erf(', ...
+                    'diff(', 'adl(', '(', ')'});
+
+% Filter out the numbers and punctuation.
+rhs_(cellfun(@(x) all(isstrprop(x, 'digit')+isstrprop(x, 'punct')), rhs_)) = [];
+
+% Get list of parameters.
+pnames = DynareModel.param_names;
+pnames = intersect(rhs_, pnames);
+
+% Get list of endogenous variables.
+enames = DynareModel.endo_names;
+enames = intersect(rhs_, enames);
+
+% Get list of exogenous variables
+xnames = DynareModel.exo_names;
+xnames = intersect(rhs_, xnames);
+
+% Decide if we are dealing with a dynamic model. If so, the lhs variable
+% already belongs to enames, we remove this variable from enames. 
+id = strmatch(lhs, enames, 'exact');
+if ~isempty(id)
+    enames(id) = [];
+end
+
+% Add lhs variable in first position of enames.
+enames = [lhs; enames];
+
+% Returns vector of indices for parameters endogenous and exogenous
+% variables if required.
+if nargout>3
+    p = length(pnames);
+    pid = zeros(p, 1);
+    for i = 1:p
+        pid(i) = strmatch(pnames{i}, DynareModel.param_names, 'exact');
+    end
+    p = length(enames);
+    eid = zeros(p, 1);
+    for i = 1:p
+        eid(i) = strmatch(enames{i}, DynareModel.endo_names, 'exact');
+    end
+    p = length(xnames);
+    xid = zeros(p, 1);
+    for i = 1:p
+        xid(i) = strmatch(xnames{i}, DynareModel.exo_names, 'exact');
+    end
+end
\ No newline at end of file