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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"How to make plt.step() draw between pre-defined bins?","articleBody":"\u003c!--To help us understand and resolve your issue, please fill out the form to the best of your ability.--\u003e\r\n\u003c!--You can feel free to delete the sections that do not apply.--\u003e\r\n\r\n### Bug report\r\nThe docstring for `plt.step()` states that when `where='post'`: \r\n- The y value is continued constantly to the right from every x position, i.e. the interval [x[i], x[i+1]) has the value y[i].\"\r\n\r\nSo if I have a len(2) y array, I should expect the last element to be continued constantly from x[1] to x[2], which means x must be a len(3) array. This makes sense, because x here specifies the edges of the bins. Specifying e.g. `y=[1, 2]` and `x=[0, 1, 4]` doesn't work however:\r\n\r\n\u003c!--A short 1-2 sentences that succinctly describes the bug--\u003e\r\n\r\n**Code for reproduction**\r\n\r\n\u003c!--A minimum code snippet required to reproduce the bug.\r\nPlease make sure to minimize the number of dependencies required, and provide\r\nany necessary plotted data.\r\nAvoid using threads, as Matplotlib is (explicitly) not thread-safe.--\u003e\r\n\r\n```python\r\nimport numpy as np\r\nimport matplotlib.pyplot as plt\r\n\r\ndata = [1, 2]\r\nbin_edges = [0, 1, 4]\r\n\r\nfig, ax = plt.subplots()\r\nax.step(data, bin_edges, where='post')\r\n\r\n```\r\n\r\n**Actual outcome**\r\n\r\n\u003c!--The output produced by the above code, which may be a screenshot, console output, etc.--\u003e\r\n\r\n```\r\n  File \"test.py\", line 8, in \u003cmodule\u003e\r\n    ax.step(data, bin_edges, where='post')\r\n  File \"/Users/dstansby/miniconda3/envs/dev/lib/python3.8/site-packages/matplotlib/axes/_axes.py\", line 2110, in step\r\n    return self.plot(x, y, *args, data=data, **kwargs)\r\n  File \"/Users/dstansby/miniconda3/envs/dev/lib/python3.8/site-packages/matplotlib/axes/_axes.py\", line 1646, in plot\r\n    lines = [*self._get_lines(*args, data=data, **kwargs)]\r\n  File \"/Users/dstansby/miniconda3/envs/dev/lib/python3.8/site-packages/matplotlib/axes/_base.py\", line 216, in __call__\r\n    yield from self._plot_args(this, kwargs)\r\n  File \"/Users/dstansby/miniconda3/envs/dev/lib/python3.8/site-packages/matplotlib/axes/_base.py\", line 342, in _plot_args\r\n    raise ValueError(f\"x and y must have same first dimension, but \"\r\nValueError: x and y must have same first dimension, but have shapes (2,) and (3,)\r\n```\r\n\r\n**Expected outcome**\r\n\r\nThe bins should be drawn between [0, 1] and [1, 4].\r\n\r\n**Matplotlib version**\r\n\u003c!--Please specify your platform and versions of the relevant libraries you are using:--\u003e\r\n  * Operating system: macos 10.15.4\r\n  * Matplotlib version: 3.2.1, installed from pip\r\n  * Matplotlib backend (`print(matplotlib.get_backend())`): Qt5Agg\r\n  * Python version: 3.8.2\r\n\r\n\u003c!--Please tell us how you installed matplotlib and python e.g., from source, pip, conda--\u003e\r\n\u003c!--If you installed from conda, please specify which channel you used if not the default--\u003e\r\n\r\n","author":{"url":"https://github.com/dstansby","@type":"Person","name":"dstansby"},"datePublished":"2020-05-28T13:10:30.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":5},"url":"https://github.com/17529/matplotlib/issues/17529"}