def _make_var_names(exog): if hasattr(exog, "name"): var_names = exog.name elif hasattr(exog, "columns"): var_names = exog.columns else: raise ValueError("exog is not a Series or DataFrame or is unnamed.") try: var_names = " ".join(var_names) except TypeError: # cannot have names that are numbers, pandas default from statsmodels.base.data import _make_exog_names if exog.ndim == 1: var_names = "x1" else: var_names = " ".join(_make_exog_names(exog)) return var_names