René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Missing labels from forced_response output","articleBody":"Hi,\r\n\r\nI wrote a state-space system representation with labels, like:\r\n\r\n``` Python\r\nsys = ct.ss(\r\n  A, B, C, D,\r\n  name=\"motor\",\r\n  states=(\"Ia\", \"Wm\"),\r\n  inputs=(\"Va\", \"Tl\"),\r\n  outputs=(\"Ia\", \"Wm\", \"Va\", \"Tl\"),\r\n)\r\n```\r\n\r\nBut after simulating it, the result (a `TimeResponseData`), lacks information about the labels of the simulated system:\r\n``` Python\r\nT = np.linspace(0, 0.360, 360)\r\nVa = np.ones_like(T) * 36\r\nTl = np.linspace(0, 15, len(T))\r\n\r\nres = ct.forced_response(motor, T, U=[Va, Tl], X0=[0, 0])\r\nprint(res.output_labels)  # this is None\r\nprint(res.input_labels)  # this is None\r\nprint(res.state_labels)  # this is None\r\n```\r\n\r\nI wanted to use `.to_pandas()`, and after assigning it manually, it works, so it's probably just a matter of passing it forward internally in the code:\r\n``` Python\r\nres.output_labels = motor.output_labels\r\nres.input_labels = motor.input_labels\r\nres.state_labels = motor.state_labels\r\ndf = res.to_pandas().set_index(\"time\")\r\n```\r\n\r\nFor completeness, this is the error if I try to use `.to_pandass()` without the abovementioned workaround:\r\n\r\n``` Python\r\n    648 # Create a dict for setting up the data frame\r\n    649 data = {'time': self.time}\r\n    650 data.update(\r\n--\u003e 651     {name: self.u[i] for i, name in enumerate(self.input_labels)})\r\n    652 data.update(\r\n    653     {name: self.y[i] for i, name in enumerate(self.output_labels)})\r\n    654 data.update(\r\n    655     {name: self.x[i] for i, name in enumerate(self.state_labels)})\r\n\r\nTypeError: 'NoneType' object is not iterable\r\n```\r\n\r\nThanks","author":{"url":"https://github.com/joaoantoniocardoso","@type":"Person","name":"joaoantoniocardoso"},"datePublished":"2023-05-20T16:37:36.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/891/python-control/issues/891"}