# -*- coding: utf-8 -*-
"""\
Force and Force coefficients interface
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Provides pythonic interface to OpenFOAM's `Forces <https://www.openfoam.com/documentation/guides/latest/doc/guide-function-objects-forces.html>`_
function objects.
"""
import re
from io import StringIO
from pathlib import Path
import pandas as pd
from .funcobj import FunctionObject
[docs]class ForceCoeffs(FunctionObject):
"""
The class retrieves data from ``coefficient.dat`` file generated during a
run.
Example:
>>> post = PostProcessing() # Get the post processing instance
>>> fcoeffs = post['forceCoeffs1'] # Retrieve force coefficients object
>>> df = fcoeffs() # Dataframe for latest time instance
>>> print(df.columns) # Examine columns
"""
_funcobj_type = "forceCoeffs"
_funcobj_libs = ["forces"]
_dict_properties = [
('patches', None),
('liftDir', None),
('dragDir', None),
('pitchAxis', None),
('magUInf', None),
('lRef', None),
('Aref', None),
]
def __call__(self, time=None):
"""Load the force coefficients file and return as dataframe.
If ``time`` is provided, the force coefficients are retrieved from the
corresponding time directory. Otherwise, the data from the latest
timestep is retrieved.
Args:
time (str): Name of the time directory.
Returns:
pd.DataFrame: DataFrame corresponding to ``coefficient.dat``
Raises:
FileNotFoundError
"""
dtime = str(time) if time else self.latest_time
dpath = Path(self.root) / dtime
fname = dpath / "coefficient.dat"
if not fname.exists():
raise FileNotFoundError(
f"Force coefficients output not found: {fname}")
with open(fname, 'r') as fh:
prev = ""
for line in fh:
if line[0] != "#":
break
prev = line
cols = prev.strip("#").split()
fcoeffs = pd.read_table(
fname, delimiter=r'\s+', comment="#", names=cols)
return fcoeffs
[docs]class Forces(FunctionObject):
"""
The class retrives data from ``force.dat`` and ``moment.dat`` files
generated during a run and returns a single Pandas DataFrame containing the
following columns.
======= =====================================
Column Value
======= =====================================
Fx Total force (x-direction)
Fy Total force (y-direction)
Fz Total force (z-direction)
Fpx Pressure force (x-direction)
Fpy Pressure force (y-direction)
Fpz Pressure force (z-direction)
Fvx Viscous force (x-direction)
Fvy Viscous force (y-direction)
Fvz Viscous force (z-direction)
Mx Total moment (x-direction)
My Total moment (y-direction)
Mz Total moment (z-direction)
Mpx Pressure moment (x-direction)
Mpy Pressure moment (y-direction)
Mpz Pressure moment (z-direction)
Mvx Viscous moment (x-direction)
Mvy Viscous moment (y-direction)
Mvz Viscous moment (z-direction)
======= =====================================
Example:
>>> post = PostProcessing() # Get the post processing instance
>>> forces = post['forces1'] # Retrieve force coefficients object
>>> df = forces() # Dataframe for latest time instance
>>> print(df.columns) # Examine columns
"""
_funcobj_type = "forces"
_funcobj_libs = ["forces"]
def _parse_file(self, fname, cols):
"""Parse the file and return a dataframe"""
rexp = re.compile(r'[\(\)]')
buf = StringIO()
# Remove parenthesis from rows
with open(fname, 'r') as fh:
for line in fh:
buf.write(rexp.sub('', line))
buf.seek(0)
# Load as a dataframe
df = pd.read_table(
buf, delimiter=r'\s+', comment="#", names=cols)
return df
def _col_names(self, prefix):
"""Get column names"""
types = "x y z px py pz vx vy vz".split()
return ['Time'] + [prefix + tx for tx in types]
def __call__(self, time=None):
"""Load the forces/moments file and return a dataframe.
If ``time`` is provided, the force coefficients are retrieved from the
corresponding time directory. Otherwise, the data from the latest
timestep is retrieved.
Args:
time (str): Name of the time directory.
Returns:
pd.DataFrame: DataFrame corresponding to ``force.dat``
and ``moment.dat``
Raises:
FileNotFoundError
"""
dtime = str(time) if time else self.latest_time
dpath = Path(self.root) / dtime
forces = self._parse_file(
dpath / "force.dat",
self._col_names('F'))
moments = self._parse_file(
dpath / "moment.dat",
self._col_names('M'))
moments.drop(columns=['Time'], inplace=True)
return pd.concat([forces, moments], axis=1)