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lammps/python/lammps.py
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# ----------------------------------------------------------------------
# LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
# http://lammps.sandia.gov, Sandia National Laboratories
# Steve Plimpton, sjplimp@sandia.gov
#
# Copyright (2003) Sandia Corporation. Under the terms of Contract
# DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
# certain rights in this software. This software is distributed under
# the GNU General Public License.
#
# See the README file in the top-level LAMMPS directory.
# -------------------------------------------------------------------------
# Python wrappers on LAMMPS library via ctypes
# for python3 compatibility
from __future__ import print_function
# imports for simple LAMMPS python wrapper module "lammps"
import sys,traceback,types
from ctypes import *
from os.path import dirname,abspath,join
from inspect import getsourcefile
# imports for advanced LAMMPS python wrapper modules "PyLammps" and "IPyLammps"
from collections import namedtuple
import os
import select
import re
class lammps(object):
# detect if Python is using version of mpi4py that can pass a communicator
has_mpi4py_v2 = False
try:
from mpi4py import MPI
from mpi4py import __version__ as mpi4py_version
if mpi4py_version.split('.')[0] == '2':
has_mpi4py_v2 = True
except:
pass
# create instance of LAMMPS
def __init__(self,name="",cmdargs=None,ptr=None,comm=None):
# determine module location
modpath = dirname(abspath(getsourcefile(lambda:0)))
# load liblammps.so unless name is given.
# e.g. if name = "g++", load liblammps_g++.so
# try loading the LAMMPS shared object from the location
# of lammps.py with an absolute path (so that LD_LIBRARY_PATH
# does not need to be set for regular installations.
# fall back to loading with a relative path, which typically
# requires LD_LIBRARY_PATH to be set appropriately.
try:
if not name: self.lib = CDLL(join(modpath,"liblammps.so"),RTLD_GLOBAL)
else: self.lib = CDLL(join(modpath,"liblammps_%s.so" % name),RTLD_GLOBAL)
except:
if not name: self.lib = CDLL("liblammps.so",RTLD_GLOBAL)
else: self.lib = CDLL("liblammps_%s.so" % name,RTLD_GLOBAL)
# if no ptr provided, create an instance of LAMMPS
# don't know how to pass an MPI communicator from PyPar
# but we can pass an MPI communicator from mpi4py v2.0.0 and later
# no_mpi call lets LAMMPS use MPI_COMM_WORLD
# cargs = array of C strings from args
# if ptr, then are embedding Python in LAMMPS input script
# ptr is the desired instance of LAMMPS
# just convert it to ctypes ptr and store in self.lmp
if not ptr:
# with mpi4py v2, can pass MPI communicator to LAMMPS
# need to adjust for type of MPI communicator object
# allow for int (like MPICH) or void* (like OpenMPI)
if lammps.has_mpi4py_v2 and comm != None:
if lammps.MPI._sizeof(lammps.MPI.Comm) == sizeof(c_int):
MPI_Comm = c_int
else:
MPI_Comm = c_void_p
narg = 0
cargs = 0
if cmdargs:
cmdargs.insert(0,"lammps.py")
narg = len(cmdargs)
for i in range(narg):
if type(cmdargs[i]) is str:
cmdargs[i] = cmdargs[i].encode()
cargs = (c_char_p*narg)(*cmdargs)
self.lib.lammps_open.argtypes = [c_int, c_char_p*narg, \
MPI_Comm, c_void_p()]
else:
self.lib.lammps_open.argtypes = [c_int, c_int, \
MPI_Comm, c_void_p()]
self.lib.lammps_open.restype = None
self.opened = 1
self.lmp = c_void_p()
comm_ptr = lammps.MPI._addressof(comm)
comm_val = MPI_Comm.from_address(comm_ptr)
self.lib.lammps_open(narg,cargs,comm_val,byref(self.lmp))
else:
self.opened = 1
if cmdargs:
cmdargs.insert(0,"lammps.py")
narg = len(cmdargs)
for i in range(narg):
if type(cmdargs[i]) is str:
cmdargs[i] = cmdargs[i].encode()
cargs = (c_char_p*narg)(*cmdargs)
self.lmp = c_void_p()
self.lib.lammps_open_no_mpi(narg,cargs,byref(self.lmp))
else:
self.lmp = c_void_p()
self.lib.lammps_open_no_mpi(0,None,byref(self.lmp))
# could use just this if LAMMPS lib interface supported it
# self.lmp = self.lib.lammps_open_no_mpi(0,None)
else:
if isinstance(ptr,lammps):
# magic to convert ptr to ctypes ptr
pythonapi.PyCObject_AsVoidPtr.restype = c_void_p
pythonapi.PyCObject_AsVoidPtr.argtypes = [py_object]
self.lmp = c_void_p(pythonapi.PyCObject_AsVoidPtr(ptr))
else:
self.lmp = None
raise TypeError('Unsupported type passed as "ptr"')
def __del__(self):
if self.lmp and self.opened: self.lib.lammps_close(self.lmp)
def close(self):
if self.opened: self.lib.lammps_close(self.lmp)
self.lmp = None
def version(self):
return self.lib.lammps_version(self.lmp)
def file(self,file):
file = file.encode()
self.lib.lammps_file(self.lmp,file)
def command(self,cmd):
cmd = cmd.encode()
self.lib.lammps_command(self.lmp,cmd)
def extract_global(self,name,type):
name = name.encode()
if type == 0:
self.lib.lammps_extract_global.restype = POINTER(c_int)
elif type == 1:
self.lib.lammps_extract_global.restype = POINTER(c_double)
else: return None
ptr = self.lib.lammps_extract_global(self.lmp,name)
return ptr[0]
def extract_atom(self,name,type):
name = name.encode()
if type == 0:
self.lib.lammps_extract_atom.restype = POINTER(c_int)
elif type == 1:
self.lib.lammps_extract_atom.restype = POINTER(POINTER(c_int))
elif type == 2:
self.lib.lammps_extract_atom.restype = POINTER(c_double)
elif type == 3:
self.lib.lammps_extract_atom.restype = POINTER(POINTER(c_double))
else: return None
ptr = self.lib.lammps_extract_atom(self.lmp,name)
return ptr
def extract_compute(self,id,style,type):
id = id.encode()
if type == 0:
if style > 0: return None
self.lib.lammps_extract_compute.restype = POINTER(c_double)
ptr = self.lib.lammps_extract_compute(self.lmp,id,style,type)
return ptr[0]
if type == 1:
self.lib.lammps_extract_compute.restype = POINTER(c_double)
ptr = self.lib.lammps_extract_compute(self.lmp,id,style,type)
return ptr
if type == 2:
self.lib.lammps_extract_compute.restype = POINTER(POINTER(c_double))
ptr = self.lib.lammps_extract_compute(self.lmp,id,style,type)
return ptr
return None
# in case of global datum, free memory for 1 double via lammps_free()
# double was allocated by library interface function
def extract_fix(self,id,style,type,i=0,j=0):
id = id.encode()
if style == 0:
self.lib.lammps_extract_fix.restype = POINTER(c_double)
ptr = self.lib.lammps_extract_fix(self.lmp,id,style,type,i,j)
result = ptr[0]
self.lib.lammps_free(ptr)
return result
elif (style == 1) or (style == 2):
if type == 1:
self.lib.lammps_extract_fix.restype = POINTER(c_double)
elif type == 2:
self.lib.lammps_extract_fix.restype = POINTER(POINTER(c_double))
else:
return None
ptr = self.lib.lammps_extract_fix(self.lmp,id,style,type,i,j)
return ptr
else:
return None
# free memory for 1 double or 1 vector of doubles via lammps_free()
# for vector, must copy nlocal returned values to local c_double vector
# memory was allocated by library interface function
def extract_variable(self,name,group,type):
name = name.encode()
group = group.encode()
if type == 0:
self.lib.lammps_extract_variable.restype = POINTER(c_double)
ptr = self.lib.lammps_extract_variable(self.lmp,name,group)
result = ptr[0]
self.lib.lammps_free(ptr)
return result
if type == 1:
self.lib.lammps_extract_global.restype = POINTER(c_int)
nlocalptr = self.lib.lammps_extract_global(self.lmp,"nlocal".encode())
nlocal = nlocalptr[0]
result = (c_double*nlocal)()
self.lib.lammps_extract_variable.restype = POINTER(c_double)
ptr = self.lib.lammps_extract_variable(self.lmp,name,group)
for i in range(nlocal): result[i] = ptr[i]
self.lib.lammps_free(ptr)
return result
return None
# set variable value
# value is converted to string
# returns 0 for success, -1 if failed
def set_variable(self,name,value):
name = name.encode()
value = str(value).encode()
return self.lib.lammps_set_variable(self.lmp,name,str(value))
# return total number of atoms in system
def get_natoms(self):
return self.lib.lammps_get_natoms(self.lmp)
# return vector of atom properties gathered across procs, ordered by atom ID
def gather_atoms(self,name,type,count):
name = name.encode()
natoms = self.lib.lammps_get_natoms(self.lmp)
if type == 0:
data = ((count*natoms)*c_int)()
self.lib.lammps_gather_atoms(self.lmp,name,type,count,data)
elif type == 1:
data = ((count*natoms)*c_double)()
self.lib.lammps_gather_atoms(self.lmp,name,type,count,data)
else: return None
return data
# scatter vector of atom properties across procs, ordered by atom ID
# assume vector is of correct type and length, as created by gather_atoms()
def scatter_atoms(self,name,type,count,data):
name = name.encode()
self.lib.lammps_scatter_atoms(self.lmp,name,type,count,data)
####################################################################################
# Alternative Python Wrapper
# Written by Richard Berger <richard.berger@temple.edu>
####################################################################################
class OutputCapture(object):
""" Utility class to capture LAMMPS library output """
def __init__(self):
self.stdout_pipe_read, self.stdout_pipe_write = os.pipe()
self.stdout_fd = 1
def __enter__(self):
self.stdout = os.dup(self.stdout_fd)
os.dup2(self.stdout_pipe_write, self.stdout_fd)
return self
def __exit__(self, type, value, tracebac):
os.dup2(self.stdout, self.stdout_fd)
# check if we have more to read from the pipe
def more_data(self, pipe):
r, _, _ = select.select([pipe], [], [], 0)
return bool(r)
# read the whole pipe
def read_pipe(self, pipe):
out = ""
while self.more_data(pipe):
out += os.read(pipe, 1024).decode()
return out
@property
def output(self):
return self.read_pipe(self.stdout_pipe_read)
class Variable(object):
def __init__(self, lammps_wrapper_instance, name, style, definition):
self.wrapper = lammps_wrapper_instance
self.name = name
self.style = style
self.definition = definition.split()
@property
def value(self):
if self.style == 'atom':
return list(self.wrapper.lmp.extract_variable(self.name, "all", 1))
else:
value = self.wrapper.lmp_print('"${%s}"' % self.name).strip()
try:
return float(value)
except ValueError:
return value
class AtomList(object):
def __init__(self, lammps_wrapper_instance):
self.lmp = lammps_wrapper_instance
self.natoms = self.lmp.system.natoms
def __getitem__(self, index):
return Atom(self.lmp, index + 1)
class Atom(object):
def __init__(self, lammps_wrapper_instance, index):
self.lmp = lammps_wrapper_instance
self.index = index
@property
def id(self):
return int(self.lmp.eval("id[%d]" % self.index))
@property
def type(self):
return int(self.lmp.eval("type[%d]" % self.index))
@property
def mol(self):
return self.lmp.eval("mol[%d]" % self.index)
@property
def mass(self):
return self.lmp.eval("mass[%d]" % self.index)
@property
def position(self):
return (self.lmp.eval("x[%d]" % self.index),
self.lmp.eval("y[%d]" % self.index),
self.lmp.eval("z[%d]" % self.index))
@property
def velocity(self):
return (self.lmp.eval("vx[%d]" % self.index),
self.lmp.eval("vy[%d]" % self.index),
self.lmp.eval("vz[%d]" % self.index))
@property
def force(self):
return (self.lmp.eval("fx[%d]" % self.index),
self.lmp.eval("fy[%d]" % self.index),
self.lmp.eval("fz[%d]" % self.index))
@property
def charge(self):
return self.lmp.eval("q[%d]" % self.index)
class PyLammps(object):
"""
More Python-like wrapper for LAMMPS (e.g., for iPython)
See examples/ipython for usage
"""
def __init__(self,name="",cmdargs=None,ptr=None,comm=None):
if ptr:
self.lmp = ptr
else:
self.lmp = lammps(name=name,cmdargs=cmdargs,ptr=None,comm=comm)
print("LAMMPS output is captured by PyLammps wrapper")
def __del__(self):
self.lmp.close()
self.lmp = None
def close(self):
self.lmp.close()
self.lmp = None
def version(self):
return self.lmp.version()
def file(self,file):
self.lmp.file(file)
def command(self,cmd):
self.lmp.command(cmd)
@property
def atoms(self):
return AtomList(self)
@property
def system(self):
output = self.info("system")
d = self._parse_info_system(output)
return namedtuple('System', d.keys())(*d.values())
@property
def communication(self):
output = self.info("communication")
d = self._parse_info_communication(output)
return namedtuple('Communication', d.keys())(*d.values())
@property
def computes(self):
output = self.info("computes")
return self._parse_element_list(output)
@property
def dumps(self):
output = self.info("dumps")
return self._parse_element_list(output)
@property
def fixes(self):
output = self.info("fixes")
return self._parse_element_list(output)
@property
def groups(self):
output = self.info("groups")
return self._parse_groups(output)
@property
def variables(self):
output = self.info("variables")
vars = {}
for v in self._parse_element_list(output):
vars[v['name']] = Variable(self, v['name'], v['style'], v['def'])
return vars
def eval(self, expr):
value = self.lmp_print('"$(%s)"' % expr).strip()
try:
return float(value)
except ValueError:
return value
def _split_values(self, line):
return [x.strip() for x in line.split(',')]
def _get_pair(self, value):
return [x.strip() for x in value.split('=')]
def _parse_info_system(self, output):
lines = output[6:-2]
system = {}
for line in lines:
if line.startswith("Units"):
system['units'] = self._get_pair(line)[1]
elif line.startswith("Atom style"):
system['atom_style'] = self._get_pair(line)[1]
elif line.startswith("Atom map"):
system['atom_map'] = self._get_pair(line)[1]
elif line.startswith("Atoms"):
parts = self._split_values(line)
system['natoms'] = int(self._get_pair(parts[0])[1])
system['ntypes'] = int(self._get_pair(parts[1])[1])
system['style'] = self._get_pair(parts[2])[1]
elif line.startswith("Kspace style"):
system['kspace_style'] = self._get_pair(line)[1]
elif line.startswith("Dimensions"):
system['dimensions'] = int(self._get_pair(line)[1])
elif line.startswith("Orthogonal box"):
system['orthogonal_box'] = [float(x) for x in self._get_pair(line)[1].split('x')]
elif line.startswith("Boundaries"):
system['boundaries'] = self._get_pair(line)[1]
elif line.startswith("xlo"):
keys, values = [self._split_values(x) for x in self._get_pair(line)]
for key, value in zip(keys, values):
system[key] = float(value)
elif line.startswith("ylo"):
keys, values = [self._split_values(x) for x in self._get_pair(line)]
for key, value in zip(keys, values):
system[key] = float(value)
elif line.startswith("zlo"):
keys, values = [self._split_values(x) for x in self._get_pair(line)]
for key, value in zip(keys, values):
system[key] = float(value)
elif line.startswith("Molecule type"):
system['molecule_type'] = self._get_pair(line)[1]
elif line.startswith("Bonds"):
parts = self._split_values(line)
system['nbonds'] = int(self._get_pair(parts[0])[1])
system['nbondtypes'] = int(self._get_pair(parts[1])[1])
system['bond_style'] = self._get_pair(parts[2])[1]
elif line.startswith("Angles"):
parts = self._split_values(line)
system['nangles'] = int(self._get_pair(parts[0])[1])
system['nangletypes'] = int(self._get_pair(parts[1])[1])
system['angle_style'] = self._get_pair(parts[2])[1]
elif line.startswith("Dihedrals"):
parts = self._split_values(line)
system['ndihedrals'] = int(self._get_pair(parts[0])[1])
system['nangletypes'] = int(self._get_pair(parts[1])[1])
system['dihedral_style'] = self._get_pair(parts[2])[1]
elif line.startswith("Impropers"):
parts = self._split_values(line)
system['nimpropers'] = int(self._get_pair(parts[0])[1])
system['nimpropertypes'] = int(self._get_pair(parts[1])[1])
system['improper_style'] = self._get_pair(parts[2])[1]
return system
def _parse_info_communication(self, output):
lines = output[6:-3]
comm = {}
for line in lines:
if line.startswith("MPI library"):
comm['mpi_version'] = line.split(':')[1].strip()
elif line.startswith("Comm style"):
parts = self._split_values(line)
comm['comm_style'] = self._get_pair(parts[0])[1]
comm['comm_layout'] = self._get_pair(parts[1])[1]
elif line.startswith("Processor grid"):
comm['proc_grid'] = [int(x) for x in self._get_pair(line)[1].split('x')]
elif line.startswith("Communicate velocities for ghost atoms"):
comm['ghost_velocity'] = (self._get_pair(line)[1] == "yes")
elif line.startswith("Nprocs"):
parts = self._split_values(line)
comm['nprocs'] = int(self._get_pair(parts[0])[1])
comm['nthreads'] = int(self._get_pair(parts[1])[1])
return comm
def _parse_element_list(self, output):
lines = output[6:-3]
elements = []
for line in lines:
element_info = self._split_values(line.split(':')[1].strip())
element = {'name': element_info[0]}
for key, value in [self._get_pair(x) for x in element_info[1:]]:
element[key] = value
elements.append(element)
return elements
def _parse_groups(self, output):
lines = output[6:-3]
groups = []
group_pattern = re.compile(r"(?P<name>.+) \((?P<type>.+)\)")
for line in lines:
m = group_pattern.match(line.split(':')[1].strip())
group = {'name': m.group('name'), 'type': m.group('type')}
groups.append(group)
return groups
def lmp_print(self, s):
""" needed for Python2 compatibility, since print is a reserved keyword """
return self.__getattr__("print")(s)
def __getattr__(self, name):
def handler(*args, **kwargs):
cmd_args = [name] + [str(x) for x in args]
with OutputCapture() as capture:
self.lmp.command(' '.join(cmd_args))
output = capture.output
lines = output.splitlines()
if len(lines) > 1:
return lines
elif len(lines) == 1:
return lines[0]
return None
return handler
class IPyLammps(PyLammps):
"""
iPython wrapper for LAMMPS which adds embedded graphics capabilities
"""
def __init__(self, lmp=lammps()):
super(IPyLammps, self).__init__(lmp)
def image(self, filename="snapshot.png", group="all", color="type", diameter="type",
size=None, view=None, center=None, up=None, zoom=1.0):
cmd_args = [group, "image", filename, color, diameter]
if size:
width = size[0]
height = size[1]
cmd_args += ["size", width, height]
if view:
theta = view[0]
phi = view[1]
cmd_args += ["view", theta, phi]
if center:
flag = center[0]
Cx = center[1]
Cy = center[2]
Cz = center[3]
cmd_args += ["center", flag, Cx, Cy, Cz]
if up:
Ux = up[0]
Uy = up[1]
Uz = up[2]
cmd_args += ["up", Ux, Uy, Uz]
if zoom:
cmd_args += ["zoom", zoom]
cmd_args.append("modify backcolor white")
self.write_dump(*cmd_args)
from IPython.core.display import Image
return Image('snapshot.png')
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