Add support for XMILE's non-negative

Add support for XMILE's non-negative flag for stocks and flows, includying also the behavior section.
Add support for XMILE's MIN and MAX with one argument.

Author: enekomartinmartinez

docs/structure/xmile_translation.rst

@@ -37,7 +37,7 @@ Xmile element
 ^^^^^^^^^^^^^
 
 .. automodule:: pysd.translators.xmile.xmile_element
-   :members: SubscriptRange, Element, Flaux, Gf, Stock
+   :members: SubscriptRange, Element, Aux, Flow, Gf, Stock
    :undoc-members:
 
 
@@ -79,7 +79,7 @@ Not all the Xmile functions are included yet. The list of supported functions is
 
 Stocks
 ^^^^^^
-Stocks are supported with any number of inflows and outflows. Stocks are translated to the AST as `IntegStructure(flows, initial_value)`.
+Stocks are supported with any number of inflows and outflows. Stocks are translated to the AST as `IntegStructure(flows, initial_value, non_negative)`. Non-negative flag is parsed for both stocks and flows, this can be set element by element or using the `behavior section <http://docs.oasis-open.org/xmile/xmile/v1.0/errata01/csprd01/xmile-v1.0-errata01-csprd01-complete.html#_Toc442104128>`_. Flows with non-negative flags are read as flows with a maximum condition, while for stocks this information is saved in the :py:class:`pysd.translators.structures.abstract_expressions.IntegStructure` object.
 
 Subscripts
 ^^^^^^^^^^

docs/tables/functions.tab

@@ -2,6 +2,8 @@ Vensim	Vensim example	Xmile	Xmile example	Abstract Syntax	Python Translation	Ven
 ABS	ABS(A)	abs	abs(A)	"CallStructure('abs', (A,))"	numpy.abs(A)
 MIN	"MIN(A, B)"	min	"min(A, B)"	"CallStructure('min', (A, B))"	"numpy.minimum(A, B)"
 MAX	"MAX(A, B)"	max	"max(A, B)"	"CallStructure('max', (A, B))"	"numpy.maximum(A, B)"
+		min	"min(A)"	"CallStructure('vmin_xmile', (A,))"	pysd.functions.vmin(A)
+		max	"max(A)"	"CallStructure('vmax_xmile', (A,))"	pysd.functions.vmax(A)
 SQRT	SQRT(A)	sqrt	sqrt(A)	"CallStructure('sqrt', (A,))"	numpy.sqrt
 EXP	EXP(A)	exp	exp(A)	"CallStructure('exp', (A,))"	numpy.exp(A)
 LN	LN(A)	ln	ln(A)	"CallStructure('ln', (A,))"	numpy.log(A)

docs/whats_new.rst

@@ -1,12 +1,14 @@
 What's New
 ==========
-v3.10.0 (2023/??/??)
+v3.10.0 (2023/04/28)
 --------------------
 New Features
 ~~~~~~~~~~~~
 - Parse TABBED ARRAYS Vensim function. (`@rogersamso <https://github.com/rogersamso>`_)
 - Add support for Vensim's `POWER <https://www.vensim.com/documentation/fn_power.html>`_ function. (`@rogersamso <https://github.com/rogersamso>`_)
 - Add possibility to pass data_files in netCDF format. (`@rogersamso <https://github.com/rogersamso>`_)
+- Add support for XMILE's non-negative flows and stocks. (`@enekomartinmartinez <https://github.com/enekomartinmartinez>`_)
+- Add support for XMILE's MIN and MAX functions with one argument. (`@enekomartinmartinez <https://github.com/enekomartinmartinez>`_)
 
 Breaking changes
 ~~~~~~~~~~~~~~~~
@@ -22,6 +24,7 @@ Bug fixes
 Documentation
 ~~~~~~~~~~~~~
 - Add information about slack channel https://slofile.com/slack/sdtoolsandmet-slj3251. (`@enekomartinmartinez <https://github.com/enekomartinmartinez>`_)
+- Update XMILE stocks section. (`@enekomartinmartinez <https://github.com/enekomartinmartinez>`_)
 
 Performance
 ~~~~~~~~~~~
@@ -30,6 +33,7 @@ Internal Changes
 ~~~~~~~~~~~~~~~~
 - Add a weekly scheduled run to all CI workflows, which run each Monday at 06:00 UTC. (`@EwoutH <https://github.com/EwoutH>`_)
 - Fix CI pipeline for Python 3.11 and remove Python 3.10 pipeline in favour of 3.11. (`@kinow <https://github.com/kinow>`_)
+- Add non_negative argument in :py:class:`pysd.translators.structures.abstract_expressions.IntegStructure`. (`@enekomartinmartinez <https://github.com/enekomartinmartinez>`_)
 
 v3.9.1 (2023/03/11)
 -------------------

pysd/_version.py

@@ -1 +1 @@
-__version__ = "3.9.1"
+__version__ = "3.10.0"

pysd/builders/python/python_expressions_builder.py

@@ -1195,6 +1195,7 @@ def __init__(self, integ_str: IntegStructure, component: object):
             "flow": integ_str.flow,
             "initial": integ_str.initial
         }
+        self.non_negative = integ_str.non_negative
 
     def build(self, arguments: dict) -> BuildAST:
         """
@@ -1213,7 +1214,6 @@ def build(self, arguments: dict) -> BuildAST:
         """
         self.component.type = "Stateful"
         self.component.subtype = "Integ"
-        self.section.imports.add("statefuls", "Integ")
 
         arguments["initial"].reshape(
             self.section.subscripts, self.def_subs, True)
@@ -1224,11 +1224,24 @@ def build(self, arguments: dict) -> BuildAST:
             self.element.identifier, prefix="_integ")
 
         # Create the object
-        self.element.objects[arguments["name"]] = {
-            "name": arguments["name"],
-            "expression": "%(name)s = Integ(lambda: %(flow)s, "
-                          "lambda: %(initial)s, '%(name)s')" % arguments
-        }
+        if self.non_negative:
+            # Non-negative stocks
+            self.section.imports.add("statefuls", "NonNegativeInteg")
+            self.element.objects[arguments["name"]] = {
+                "name": arguments["name"],
+                "expression": "%(name)s = NonNegativeInteg("
+                              "lambda: %(flow)s, "
+                              "lambda: %(initial)s, '%(name)s')" % arguments
+            }
+        else:
+            # Regular stocks
+            self.section.imports.add("statefuls", "Integ")
+            self.element.objects[arguments["name"]] = {
+                "name": arguments["name"],
+                "expression": "%(name)s = Integ(lambda: %(flow)s, "
+                              "lambda: %(initial)s, '%(name)s')" % arguments
+            }
+
         # Add other dependencies
         self.element.other_dependencies[arguments["name"]] = {
             "initial": arguments["initial"].calls,

pysd/builders/python/python_functions.py

@@ -35,6 +35,8 @@
     "sum": ("sum(%(0)s, dim=%(axis)s)", ("functions", "sum")),
     "vmax": ("vmax(%(0)s, dim=%(axis)s)", ("functions", "vmax")),
     "vmin": ("vmin(%(0)s, dim=%(axis)s)", ("functions", "vmin")),
+    "vmax_xmile": ("vmax(%(0)s)", ("functions", "vmax")),
+    "vmin_xmile": ("vmin(%(0)s)", ("functions", "vmin")),
     "vector_select": (
         "vector_select(%(0)s, %(1)s, %(axis)s, %(2)s, %(3)s, %(4)s)",
         ("functions", "vector_select")

pysd/py_backend/statefuls.py

@@ -98,6 +98,32 @@ def export(self):
         return {'state': self.state, 'shape_info': self.shape_info}
 
 
+class NonNegativeInteg(Integ):
+    """
+    Implements non negative INTEG function.
+
+    Parameters
+    ----------
+    ddt: callable
+        Derivate to integrate.
+    initial_value: callable
+        Initial value.
+    py_name: str
+        Python name to identify the object.
+
+    Attributes
+    ----------
+    state: float or xarray.DataArray
+        Current state of the object. Value of the stock.
+
+    """
+    def __init__(self, ddt, initial_value, py_name):
+        super().__init__(ddt, initial_value, py_name)
+
+    def update(self, state):
+        self.state = np.maximum(state, 0)
+
+
 class Delay(DynamicStateful):
     """
     Implements DELAY function.

pysd/translators/structures/abstract_expressions.py

@@ -9,7 +9,7 @@
 anything else.
 """
 from dataclasses import dataclass
-from typing import Union
+from typing import Union, Optional
 
 
 class AbstractSyntax:
@@ -230,10 +230,13 @@ class IntegStructure(AbstractSyntax):
         The flow of the stock.
     initial: AST
         The initial value of the stock.
+    non_negative: bool (optional)
+        If True the stock cannot be negative. Default is False.
 
     """
     flow: Union[AbstractSyntax, float]
     initial: Union[AbstractSyntax, float]
+    non_negative: Optional[bool] = False
 
     def __str__(self) -> str:  # pragma: no cover
         return "IntegStructure:\n\t%s,\n\t%s" % (

pysd/translators/vensim/vensim_element.py

@@ -1,7 +1,7 @@
 """
 The Element class allows parsing the LHS of a model equation.
 Depending on the LHS value, either a SubscriptRange object or a Component
-object will be returned. There are 4 components types:
+object will be returned. There are four components types:
 
 - Component: Regular component, defined with '='.
 - UnchangeableConstant: Unchangeable constant, defined with '=='.