From c4d0f07093310ac0d3e8cf6ee9c3c35b5a640099 Mon Sep 17 00:00:00 2001
From: Richard Berger <richard.berger@temple.edu>
Date: Fri, 12 May 2017 00:29:58 -0400
Subject: [PATCH] Allow fix python to only execute every N steps
---
doc/src/fix_python.txt | 13 +++++++------
examples/python/in.fix_python | 4 ++--
src/PYTHON/fix_python.cpp | 13 +++++++++----
3 files changed, 18 insertions(+), 12 deletions(-)
diff --git a/doc/src/fix_python.txt b/doc/src/fix_python.txt
index f69ff41bfa..8b921bc999 100644
--- a/doc/src/fix_python.txt
+++ b/doc/src/fix_python.txt
@@ -10,13 +10,14 @@ fix python command :h3
[Syntax:]
-fix ID group-ID python callback function_name :pre
+fix ID group-ID python N callback function_name :pre
ID, group-ID are ignored by this fix :ulb,l
python = style name of this fix command :l
+N = execute every N steps :l
callback = {post_force} or {end_of_step} :l
- {post_force} = callback after force computations on atoms
- {end_of_step} = callback after each time step :pre
+ {post_force} = callback after force computations on atoms every N time steps
+ {end_of_step} = callback after each N time steps :pre
:ule
[Examples:]
@@ -35,14 +36,14 @@ def end_of_step_callback(lammps_ptr):
# access LAMMPS state using Python interface
""" :pre
-fix pf all python post_force post_force_callback
-fix eos all python end_of_step end_of_step_callback :pre
+fix pf all python 50 post_force post_force_callback
+fix eos all python 50 end_of_step end_of_step_callback :pre
[Description:]
This fix allows you to call a Python function during a simulation run.
The callback is either executed after forces have been applied to atoms
-or at the end of each time step.
+or at the end of every N time steps.
Callback functions must be declared in the global scope of the
active Python interpreter. This can either be done by defining it
diff --git a/examples/python/in.fix_python b/examples/python/in.fix_python
index 426b456688..c98029a63b 100644
--- a/examples/python/in.fix_python
+++ b/examples/python/in.fix_python
@@ -33,8 +33,8 @@ def post_force_callback(lmp, v):
"""
fix 1 all nve
-fix 2 all python end_of_step end_of_step_callback
-fix 3 all python post_force post_force_callback
+fix 2 all python 50 end_of_step end_of_step_callback
+fix 3 all python 50 post_force post_force_callback
#dump id all atom 50 dump.melt
diff --git a/src/PYTHON/fix_python.cpp b/src/PYTHON/fix_python.cpp
index 08beb511cb..4f437b7488 100644
--- a/src/PYTHON/fix_python.cpp
+++ b/src/PYTHON/fix_python.cpp
@@ -36,14 +36,17 @@ using namespace FixConst;
FixPython::FixPython(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg)
{
- if (narg != 5) error->all(FLERR,"Illegal fix python command");
+ if (narg != 6) error->all(FLERR,"Illegal fix python command");
+
+ nevery = force->inumeric(FLERR,arg[3]);
+ if (nevery <= 0) error->all(FLERR,"Illegal fix python command");
// ensure Python interpreter is initialized
python->init();
- if (strcmp(arg[3],"post_force") == 0) {
+ if (strcmp(arg[4],"post_force") == 0) {
selected_callback = POST_FORCE;
- } else if (strcmp(arg[3],"end_of_step") == 0) {
+ } else if (strcmp(arg[4],"end_of_step") == 0) {
selected_callback = END_OF_STEP;
}
@@ -57,7 +60,7 @@ FixPython::FixPython(LAMMPS *lmp, int narg, char **arg) :
error->all(FLERR,"Could not initialize embedded Python");
}
- char * fname = arg[4];
+ char * fname = arg[5];
pFunc = PyObject_GetAttrString(pyMain, fname);
if (!pFunc) {
@@ -94,6 +97,8 @@ void FixPython::end_of_step()
void FixPython::post_force(int vflag)
{
+ if (update->ntimestep % nevery != 0) return;
+
PyGILState_STATE gstate = PyGILState_Ensure();
PyObject * ptr = PY_VOID_POINTER(lmp);
--
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