Interface refactoring

Find a design which is more intuitive and minimal.

codes/params/rparams.py

+from codes.params.param_transforms import (
+    complex_to_real,
+    flat_to_tb,
+    real_to_complex,
+    tb_to_flat,
+)
+
+
+def tb_to_rparams(tb):
+    """Convert a mean-field tight-binding model to a set of real parameters.
+
+    Parameters
+    ----------
+    tb : dict
+        Mean-field tight-binding model.
+
+    Returns
+    -------
+    dict
+        Real parameters.
+    """
+    return complex_to_real(tb_to_flat(tb))  # placeholder for now
+
+
+def rparams_to_tb(r_params, key_list, size):
+    """Extract mean-field tight-binding model from a set of real parameters.
+
+    Parameters
+    ----------
+    r_params : dict
+        Real parameters.
+    key_list : list
+        List of the keys of the mean-field tight-binding model, meaning all the
+        hoppings.
+    size : tuple
+        Shape of the mean-field tight-binding model.
+
+    Returns
+    -------
+    dict
+        Mean-field tight-binding model.
+    """
+    flat_matrix = real_to_complex(r_params)
+    return flat_to_tb(flat_matrix, (len(key_list), size, size), key_list)