def load_pip_requirements(self, files_map=None, freeze=True):
        if files_map is None:
            files_map = self.default_pip_files
        for group, requirements_txt in files_map.items():
            path = Path(requirements_txt)
            if not path.exists() and group.lower() == "all" and freeze:
                cmd = envoy.run("pip freeze")
                self[group].loads(cmd.std_out)
            elif path.exists():
                self[group].load(path)
def idq_ld(id, iq, ld, ax=0):
    """creates a surface plot of ld vs. id, iq"""
    if ax == 0:
        _create_3d_axis()
        ax = plt.gca()
    _plot_surface(ax, id, iq, np.asarray(ld)*1e3,
                  (u'Id/A', u'Iq/A', u'L d/mH'),
                  azim=120)