def load(self, filename, create_if_missing=True):
        filename = Path(filename)
        if not filename.exists() and create_if_missing:
            self.load_pip_requirements()
            with filename.open("w") as f:
                f.write(yaml.dump(self.serialized, default_flow_style=False,
                                  encoding=None))
            self.filename = filename
            return self.save(filename)
        with filename.open() as f:
            for group, requirements in yaml.load(f.read()).items():
                for requirement in requirements:
                    self[group].add(Requirement.coerce(requirement))
        self.filename = filename
def phasor(bch, ax=0):
    """create phasor plot from bch"""
    f1 = bch.machine['p']*bch.dqPar['speed']
    w1 = 2*np.pi*f1
    xd = w1*bch.dqPar['ld'][-1]
    xq = w1*bch.dqPar['lq'][-1]
    r1 = bch.machine['r1']
    i1beta_phasor(bch.dqPar['up'][-1],
                  bch.dqPar['i1'][-1], bch.dqPar['beta'][-1],
                  r1, xd, xq, ax)