def install_pip(self, package, save=True, save_dev=False):
        """Installs a pip package.

        :param save: if `True`, pins the package to the Hydrogen requirements
            YAML file.
        :param save_dev: if `True`, pins the package as a development
            dependency to the Hydrogen requirements YAML file.
        :param return: a **single** :class:`Requirement` object, representing
            the installed version of the given package.
        """
        requirement = Requirement.coerce(package)
        click.echo("pip install " + requirement.package)
        cmd = envoy.run("pip install {}".format(str(requirement)))
        if cmd.status_code == 0:
            installed_packages = get_installed_pypackages()
            package = installed_packages[requirement.package]
            requirement.version = "=={}".format(package.version)
            if save:
                self.requirements["all"].add(requirement)
            if save_dev:
                self.requirements["dev"].add(requirement)
            if save or save_dev:
                self.requirements.save()
            return requirement
        else:
            fatal(cmd.std_err)
def demag_pos(isa, pos, icur=-1, ibeta=-1, ax=0):
    """plot demag of NC/I7/ISA7 model at rotor position
    Args:
      isa: Isa7/NC object
      pos: rotor position in degree
      icur: cur amplitude index or last index if -1
      ibeta: beta angle index or last index if -1
    """
    emag = [e for e in isa.elements if e.is_magnet()]
    demag = np.array([isa.demagnetization(e, icur, ibeta)[1]
                     for e in emag])
    for i, x in enumerate(isa.pos_el_fe_induction):
        if x >= pos/180*np.pi:
            break

    hpol = demag[:, i]
    hpol[hpol == 0] = np.nan
    _contour(ax, f'Demagnetization at Pos. {round(x/np.pi*180)}° ({isa.MAGN_TEMPERATURE} °C)',
             emag, hpol, '-H / kA/m', isa)
    logger.info("Max demagnetization %f kA/m", np.nanmax(hpol))