@@ -5,7 +5,7 @@ The general goal of the project is to create a Python package that can
- trigger the Dynare Preprocessor
- apply Python algorithms to Python representation of a Dynare model
- call Julia to leverage DynareJulia algorithms and recover results as Python objects
- call Matlab/Octave to leverage Dynare Matlab/Octave algorithms and recover results as Python objects
- call MATLAB/Octave to leverage Dynare MATLAB/Octave algorithms and recover results as Python objects
## Development tasks
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@@ -13,19 +13,34 @@ The general goal of the project is to create a Python package that can
Either
- as \*.py file
-calling the bytecode library generated by the preprosessor
- as \*.py files
-by interpreting the bytecode output
#### \*.py files
The Dynare preprocessor has a generic infrastructure for handling different output languages. Currently, it supports MATLAB/Octave, C and Julia. The idea is thus to add Python as a 4th output language, leveraging the existing infrastructure.
In terms of calling interface, the preprocessor accepts a command-line option `language` whose value can be either `matlab` or `julia` (C output is subsumed in the `matlab` option value when used in combination with the `use_dll` option); this is handled in `DynareMain.cc`. A new `python` option value should be added (and the `LanguageOutputType` class enum in `ExtendedPreprocessorTypes.hh` should be expanded accordingly). Throughout the preprocessor code, the distinction between MATLAB/Octave and Julia is currently passed through a `bool julia` function argument in calling trees; this should probably be replaced by passing a `LanguageOutputType` value that covers the three languages.
The engine for manipulating and outputting symbolic algebraic expressions is located in `ExprNode.hh` and `ExprNode.cc`. In particular, there is a generic framework for outputting expressions in various contexts, depending on the programming language (MATLAB/Octave, C, Julia) and in the type of expression (dynamic expression with leads and lags, static expression, time series…), as reflected in the `ExprNodeOutputType`. For Python, the following values should be added:
-`pythonDynamicModel` (for outputting the dynamic model)
-`pythonStaticModel` (for outputting the static model)
-`pythonDynamicSteadyStateOperator` (used inside a `STEADY_STATE` operator within a dynamic model)
-`pythonSteadyStateFile` (for writing the contents of the `steady_state_model` block)
- and maybe some type for writing time series in some native Python object (similar to `matlabDseries` and `juliaTimeDataFrame`)
Once these new enums are in place, they should be handled throughout the expression writing engine, in particular:
- within the helpers `isSteadyStateOperatorOutput()`, `isSparseModelOutput()` (should always return `true` for Python), `ARRAY_SUBSCRIPT_OFFSET()` (array indexing is 0-based in Python); a new `isPythonOutput()` helper should also be created; NB: `LEFT_ARRAY_SUBSCRIPT()` and `RIGHT_ARRAY_SUBSCRIPT()` need no adjustment since Python uses brackets for array-indexing;
- in the `writeOutput()` methods of the various classes, so as to write use the correct objects and mathematical function names for the Python context
- maybe also adapt the `cost()` methods
- Adapt the Julia specific code for Python in
*`ModelTree.hh`
*`DynamicModel.cc` and `DynamicModel.hh`
*`StaticModel.cc` and `StaticModel.hh`
*`ExtendedPreprocessorTypes.hh`
*`ExprNode.hh`
*`ModelEquationBlock.cc` and `ModelEquationsBlock.hh`
* add language Python as language option in `DynareMain.cc` (see Julia option)
* the main differences between Python code and Julia code relevant here are
