Added error check and message for pipeline parameter if not found

okz12 · okz12 · commit 95b6d9f0eb3c · 2019-03-28T07:37:28.000Z
diff --git a/sklearn/pipeline.py b/sklearn/pipeline.py
@@ -254,6 +254,9 @@ def _fit(self, X, y=None, **fit_params):
                             if step is not None}
         for pname, pval in fit_params.items():
             step, param = pname.split('__', 1)
+            if step not in fit_params_steps:
+                raise TypeError("Step '{}' not found for parameter '{}'. Use naming convention step__parameter."
+                                .format(step, param))
             fit_params_steps[step][param] = pval
         Xt = X
         for step_idx, name, transformer in self._iter(with_final=False):
