Sympy potential

[ludogibbs]

Added feature:
Generating tabulated forces and energies using analytical functions
Giving a potential V(r,params),params and number of steps instead of force and energy tables can now also be interpreted correctly.

[espresso-ci]

Your pull request does not meet our code formatting rules. Specifically, I suggest you make the following changes:

diff --git a/src/python/espressomd/interactions.py b/src/python/espressomd/interactions.py
index ce94c72f8..fca4b622a 100644
--- a/src/python/espressomd/interactions.py
+++ b/src/python/espressomd/interactions.py
@@ -19,7 +19,7 @@
 
 import abc
 import enum
-from sympy import sympify, symbols,oo,nan
+from sympy import sympify, symbols, oo, nan
 import numpy as np
 from . import code_features
 from .script_interface import ScriptObjectMap, ScriptInterfaceHelper, script_interface_register
@@ -59,7 +59,6 @@ class NonBondedInteraction(ScriptInterfaceHelper, metaclass=abc.ABCMeta):
         err_msg = f"setting {self.__class__.__name__} raised an error"
         self.call_method("set_params", handle_errors_message=err_msg, **params)
 
-
     @abc.abstractmethod
     def default_params(self):
         pass
@@ -352,7 +351,7 @@ class TabulatedNonBonded(NonBondedInteraction):
 
         """
         return {}
-    
+
     def set_params(self, **kwargs):
         """Set new parameters.
 
@@ -366,16 +365,18 @@ class TabulatedNonBonded(NonBondedInteraction):
             if missing_keys:
                 raise ValueError(
                     f"Missing keys for table generation: {missing_keys}. "
-                    f"To generate energy and force tables, provide {required_keys}."
+                    f"To generate energy and force tables, provide {
+                        required_keys}."
                 )
-        
+
             # Berechnung von Energie- und Krafttabellen mit \`get_table\`
             energy_tab, force_tab = self.get_table(
                 min=params["min"],
                 max=params["max"],
                 steps=params["steps"],
                 f=params["f"],
-                **{k: v for k, v in params.items() if k not in required_keys}  # Zusätzliche Parameter
+                # Zusätzliche Parameter
+                **{k: v for k, v in params.items() if k not in required_keys}
             )
             params["energy"] = energy_tab
             params["force"] = force_tab
@@ -384,9 +385,8 @@ class TabulatedNonBonded(NonBondedInteraction):
         filtered_params = {k: params[k] for k in relevant_keys if k in params}
 
         err_msg = f"setting {self.__class__.__name__} raised an error"
-        self.call_method("set_params", handle_errors_message=err_msg, **filtered_params)
-
-        
+        self.call_method(
+            "set_params", handle_errors_message=err_msg, **filtered_params)
 
     def get_table(self, **kwargs):
         """
diff --git a/testsuite/python/tabulated_sympy.py b/testsuite/python/tabulated_sympy.py
index 7c49543b2..1cd80fec9 100644
--- a/testsuite/python/tabulated_sympy.py
+++ b/testsuite/python/tabulated_sympy.py
@@ -23,6 +23,7 @@ import espressomd.interactions
 import numpy as np
 from sympy import symbols, sympify
 
+
 class TabulatedTest(ut.TestCase):
     system = espressomd.System(box_l=3 * [10.])
     system.time_step = 0.01
@@ -34,8 +35,10 @@ class TabulatedTest(ut.TestCase):
         self.eps_ = 1.
         self.sig_ = 2.
         self.steps_ = 100
-        self.force = [-4*self.eps_*(12/r*(self.sig_/r)**12-6/r*(self.sig_/r)**6) for r in np.linspace(self.min_,self.max_,self.steps_)]
-        self.energy = [4*self.eps_*((self.sig_/r)**12-(self.sig_/r)**6) for r in np.linspace(self.min_,self.max_,self.steps_)]
+        self.force = [-4 * self.eps_ * (12 / r * (self.sig_ / r)**12 - 6 / r * (
+            self.sig_ / r)**6) for r in np.linspace(self.min_, self.max_, self.steps_)]
+        self.energy = [4 * self.eps_ * ((self.sig_ / r)**12 - (self.sig_ / r)**6)
+                       for r in np.linspace(self.min_, self.max_, self.steps_)]
         self.system.part.add(type=0, pos=[5., 5., 5.0])
         self.system.part.add(type=0, pos=[5., 5., 5.5])
 
@@ -47,13 +50,13 @@ class TabulatedTest(ut.TestCase):
         # Below cutoff
         np.testing.assert_allclose(np.copy(self.system.part.all().f), 0.0)
 
-        for i,z in enumerate(np.linspace(0, self.max_ - self.min_, self.steps_)):
+        for i, z in enumerate(np.linspace(0, self.max_ - self.min_, self.steps_)):
             if z >= self.max_ - self.min_:
                 continue
             p1.pos = [5., 5., 6. + z]
             self.system.integrator.run(0)
             np.testing.assert_allclose(
-                np.copy(p0.f), [0., 0.,self.force[i]])
+                np.copy(p0.f), [0., 0., self.force[i]])
             np.testing.assert_allclose(np.copy(p0.f), -np.copy(p1.f))
             self.assertAlmostEqual(
                 self.system.analysis.energy()['total'], self.energy[i])
@@ -61,10 +64,11 @@ class TabulatedTest(ut.TestCase):
     @utx.skipIfMissingFeatures("TABULATED")
     def test_tabulated_sympy(self):
         self.system.non_bonded_inter[0, 0].tabulated.set_params(
-            min=self.min_, max=self.max_,steps=self.steps_,sig=self.sig_,eps=self.eps_, f="4*eps*((sig/r)**12-(sig/r)**6)")
+            min=self.min_, max=self.max_, steps=self.steps_, sig=self.sig_, eps=self.eps_, f="4*eps*((sig/r)**12-(sig/r)**6)")
         self.assertEqual(
             self.system.non_bonded_inter[0, 0].tabulated.cutoff, self.max_)
         self.check()
 
+
 if __name__ == "__main__":
-    ut.main()
\ No newline at end of file
+    ut.main()

To apply these changes, please do one of the following:

• You can download a patch with my suggested changes here, inspect it and make changes manually.
• You can directly apply it to your repository by running curl https://gitlab.icp.uni-stuttgart.de/espressomd/espresso/-/jobs/376854/artifacts/raw/style.patch | git apply -.
• You can run maintainer/CI/fix_style.sh to automatically fix your coding style. This is the same command that I have executed to generate the patch above, but it requires certain tools to be installed on your computer.

You can run gitlab-runner exec docker style afterwards to check if your changes worked out properly.

Please note that there are often multiple ways to correctly format code. As I am just a robot, I sometimes fail to identify the most aesthetically pleasing way. So please look over my suggested changes and adapt them where the style does not make sense.

[espresso-ci]

Your pull request does not meet our code style rules. Pylint summary:

<unknown>:246: SyntaxWarning: invalid escape sequence '\*'
************* Module tabulated_sympy
testsuite/python/tabulated_sympy.py:24:0: W0611: Unused symbols imported from sympy (unused-import)
testsuite/python/tabulated_sympy.py:24:0: W0611: Unused sympify imported from sympy (unused-import)

You can generate these warnings with maintainer/CI/fix_style.sh. This is the same command that I have executed to generate the log above.