{"schema_version":"4.0","kind":"technical_task_solution","page":{"title":"How do you make Matplotlib is_color_like reject numeric strings before scatter raises an RGBA ValueError?","url":"https://agent-solution.dev/tasks/matplotlib-valueerror-is-color-like","manifest_url":"https://agent-solution.dev/tasks/matplotlib-valueerror-is-color-like/agent.json","description":"matplotlib/matplotlib — ValueError in is_color_like. Traceback path: lib/matplotlib/colors.py. Match the exact symbols, paths, and error text on the page.","updated_at":"2026-08-27"},"task_match":{"technology":"matplotlib/matplotlib","error_signature":"ValueError","focus_symbol":"is_color_like","focus_path":"lib/matplotlib/colors.py","problem_class":"python-traceback-repairs","statement_kind":"verbatim agent-facing issue statement","task_statement":"`is_color_like` returning erroneous value on strings of integers\n<!--To help us understand and resolve your issue, please fill out the form to the best of your ability.-->\r\n<!--You can feel free to delete the sections that do not apply.-->\r\n\r\n### Bug report\r\n\r\n**Bug summary**\r\n\r\n`matplotlib.colors.is_color_like` returns `True` on strings containing integers, even though these are invalid colours when passed to `plt.scatter` or equivalent.\r\n\r\n**Code for reproduction**\r\n\r\n<!--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.-->\r\n\r\n```python\r\nimport matplotlib\r\nimport matplotlib.pyplot as plt\r\nimport numpy as np\r\n\r\nc = np.arange(1000).astype(str)\r\nX = np.random.normal(0, 1, [1000, 2])\r\n\r\nassert all([matplotlib.colors.is_color_like(color) for color in c])\r\nplt.scatter(X[:, 0], X[:, 1], c=c)\r\n```\r\n\r\n**Actual outcome**\r\n\r\n<!--The output produced by the above code, which may be a screenshot, console output, etc.-->\r\n\r\n```\r\n>>> import matplotlib\r\n>>> import matplotlib.pyplot as plt\r\n>>> import numpy as np\r\n>>>\r\n>>> c = np.arange(1000).astype(str)\r\n>>> X = np.random.normal(0, 1, [1000, 2])\r\n>>>\r\n>>> assert all([matplotlib.colors.is_color_like(color) for color in c])\r\n>>> plt.scatter(X[:, 0], X[:, 1], c=c)\r\nTraceback (most recent call last):\r\n  File \"<stdin>\", line 1, in <module>\r\n  File \"/usr/lib/python3.7/site-packages/matplotlib/pyplot.py\", line 2864, in scatter\r\n    is not None else {}), **kwargs)\r\n  File \"/usr/lib/python3.7/site-packages/matplotlib/__init__.py\", line 1810, in inner\r\n    return func(ax, *args, **kwargs)\r\n  File \"/usr/lib/python3.7/site-packages/matplotlib/axes/_axes.py\", line 4297, in scatter\r\n    alpha=alpha\r\n  File \"/usr/lib/python3.7/site-packages/matplotlib/collections.py\", line 899, in __init__\r\n    Collection.__init__(self, **kwargs)\r\n  File \"/usr/lib/python3.7/site-packages/matplotlib/collections.py\", line 131, in __init__\r\n    self.set_facecolor(facecolors)\r\n  File \"/usr/lib/python3.7/site-packages/matplotlib/collections.py\", line 685, in set_facecolor\r\n    self._set_facecolor(c)\r\n  File \"/usr/lib/python3.7/site-packages/matplotlib/collections.py\", line 668, in _set_facecolor\r\n    self._facecolors = mcolors.to_rgba_array(c, self._alpha)\r\n  File \"/usr/lib/python3.7/site-packages/matplotlib/colors.py\", line 260, in to_rgba_array\r\n    raise ValueError(\"RGBA values should be within 0-1 range\")\r\nValueError: RGBA values should be within 0-1 range\r\n```\r\n\r\n**Expected outcome**\r\n\r\n<!--A description of the expected outcome from the code snippet-->\r\n<!--If this used to work in an earlier version of Matplotlib, please note the version it used to work on-->\r\nI would expect either the `scatter` call to successfully recognise these as colours, or the `is_color_like` calls to return `False`. The latter is what I would expect of these two.\r\n\r\n**Matplotlib version**\r\n<!--Please specify your platform and versions of the relevant libraries you are using:-->\r\n  * Operating system: Arch Linux\r\n  * Matplotlib version: 3.0.2\r\n  * Matplotlib backend (`print(matplotlib.get_backend())`): Qt5Agg\r\n  * Python version: Python 3.7.1\r\n  * Jupyter version (if applicable): N/A\r\n  * Other libraries: `numpy` 1.15.0\r\n\r\n`matplotlib` installed from `pip`. The example code runs without any errors on Windows, Python 3.6, `matplotlib` 2.2.2.\r\n<!--Please tell us how you installed matplotlib and python e.g., from source, pip, conda-->\r\n<!--If you installed from conda, please specify which channel you used if not the default-->","technical_objective":"Remove the inconsistency between Matplotlib's colour predicate and Matplotlib's colour conversion: a value for which matplotlib.colors.is_color_like reports True must be convertible by the colour conversion routines, and a value the conversion routines reject must not be reported as colour-like.","success_condition":"for strings of the form produced by np.arange(1000).astype(str), the predicate and the conversion agree, so that either both accept them or both reject them, and the previously supported string colour spellings (named colours, hex, CN cycle references, and grayscale strings) keep working unchanged.","upstream_source":{"repository":"matplotlib/matplotlib","commit":"dd18211687623c5fa57658990277440814d422f0","version":"3.0"},"primary_terms":["ValueError","is_color_like","lib/matplotlib/colors.py","matplotlib/matplotlib","matplotlib.colors.is_color_like","to_rgba_array","to_rgba","plt.scatter","set_facecolor","_set_facecolor","Collection.__init__","lib/matplotlib/collections.py"],"search_signals":["Error signature: ValueError","Traceback path: lib/matplotlib/colors.py","Repository: matplotlib/matplotlib","Issue title: ` is_color_like returning erroneous value on strings of integers `.","Symbols: matplotlib.colors.is_color_like, to_rgba_array, to_rgba, plt.scatter, set_facecolor, _set_facecolor, Collection.__init__.","Files: lib/matplotlib/colors.py, lib/matplotlib/collections.py, lib/matplotlib/axes/_axes.py, lib/matplotlib/pyplot.py.","Verbatim error string: ValueError: RGBA values should be within 0-1 range.","Reproduction: c = np.arange(1000).astype(str), plt.scatter(X[:, 0], X[:, 1], c=c), assert all([matplotlib.colors.is_color_like(color) for color in c]).","Environment details quoted in the report: Matplotlib 3.0.2, backend Qt5Agg, Python 3.7.1, numpy 1.15.0, Arch Linux, \"runs without any errors on Windows, Python 3.6, matplotlib 2.2.2\"."],"match_summary":"Matches matplotlib/matplotlib work keyed on ValueError in is_color_like.","demonstrations":null},"evidence_search":{"guide_url":"https://agent-solution.dev/tasks/matplotlib-valueerror-is-color-like/llms.txt","method":"GET","url":"https://agent-solution.dev/tasks/matplotlib-valueerror-is-color-like/search","url_template":"https://agent-solution.dev/tasks/matplotlib-valueerror-is-color-like/search?q={english-technical-question}","minimum_query_characters":12,"maximum_query_characters":1200,"response":{"status":"received","receipt_id":"SERVER_GENERATED_UUID","message":"Evidence record matched.","evidence_record":{"title":"How do you make Matplotlib is_color_like reject numeric strings before scatter raises an RGBA ValueError?","summary":"Matches matplotlib/matplotlib work keyed on ValueError in is_color_like.","task_statement":"`is_color_like` returning erroneous value on strings of integers\n<!--To help us understand and resolve your issue, please fill out the form to the best of your ability.-->\r\n<!--You can feel free to delete the sections that do not apply.-->\r\n\r\n### Bug report\r\n\r\n**Bug summary**\r\n\r\n`matplotlib.colors.is_color_like` returns `True` on strings containing integers, even though these are invalid colours when passed to `plt.scatter` or equivalent.\r\n\r\n**Code for reproduction**\r\n\r\n<!--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.-->\r\n\r\n```python\r\nimport matplotlib\r\nimport matplotlib.pyplot as plt\r\nimport numpy as np\r\n\r\nc = np.arange(1000).astype(str)\r\nX = np.random.normal(0, 1, [1000, 2])\r\n\r\nassert all([matplotlib.colors.is_color_like(color) for color in c])\r\nplt.scatter(X[:, 0], X[:, 1], c=c)\r\n```\r\n\r\n**Actual outcome**\r\n\r\n<!--The output produced by the above code, which may be a screenshot, console output, etc.-->\r\n\r\n```\r\n>>> import matplotlib\r\n>>> import matplotlib.pyplot as plt\r\n>>> import numpy as np\r\n>>>\r\n>>> c = np.arange(1000).astype(str)\r\n>>> X = np.random.normal(0, 1, [1000, 2])\r\n>>>\r\n>>> assert all([matplotlib.colors.is_color_like(color) for color in c])\r\n>>> plt.scatter(X[:, 0], X[:, 1], c=c)\r\nTraceback (most recent call last):\r\n  File \"<stdin>\", line 1, in <module>\r\n  File \"/usr/lib/python3.7/site-packages/matplotlib/pyplot.py\", line 2864, in scatter\r\n    is not None else {}), **kwargs)\r\n  File \"/usr/lib/python3.7/site-packages/matplotlib/__init__.py\", line 1810, in inner\r\n    return func(ax, *args, **kwargs)\r\n  File \"/usr/lib/python3.7/site-packages/matplotlib/axes/_axes.py\", line 4297, in scatter\r\n    alpha=alpha\r\n  File \"/usr/lib/python3.7/site-packages/matplotlib/collections.py\", line 899, in __init__\r\n    Collection.__init__(self, **kwargs)\r\n  File \"/usr/lib/python3.7/site-packages/matplotlib/collections.py\", line 131, in __init__\r\n    self.set_facecolor(facecolors)\r\n  File \"/usr/lib/python3.7/site-packages/matplotlib/collections.py\", line 685, in set_facecolor\r\n    self._set_facecolor(c)\r\n  File \"/usr/lib/python3.7/site-packages/matplotlib/collections.py\", line 668, in _set_facecolor\r\n    self._facecolors = mcolors.to_rgba_array(c, self._alpha)\r\n  File \"/usr/lib/python3.7/site-packages/matplotlib/colors.py\", line 260, in to_rgba_array\r\n    raise ValueError(\"RGBA values should be within 0-1 range\")\r\nValueError: RGBA values should be within 0-1 range\r\n```\r\n\r\n**Expected outcome**\r\n\r\n<!--A description of the expected outcome from the code snippet-->\r\n<!--If this used to work in an earlier version of Matplotlib, please note the version it used to work on-->\r\nI would expect either the `scatter` call to successfully recognise these as colours, or the `is_color_like` calls to return `False`. The latter is what I would expect of these two.\r\n\r\n**Matplotlib version**\r\n<!--Please specify your platform and versions of the relevant libraries you are using:-->\r\n  * Operating system: Arch Linux\r\n  * Matplotlib version: 3.0.2\r\n  * Matplotlib backend (`print(matplotlib.get_backend())`): Qt5Agg\r\n  * Python version: Python 3.7.1\r\n  * Jupyter version (if applicable): N/A\r\n  * Other libraries: `numpy` 1.15.0\r\n\r\n`matplotlib` installed from `pip`. The example code runs without any errors on Windows, Python 3.6, `matplotlib` 2.2.2.\r\n<!--Please tell us how you installed matplotlib and python e.g., from source, pip, conda-->\r\n<!--If you installed from conda, please specify which channel you used if not the default-->","technical_objective":"Remove the inconsistency between Matplotlib's colour predicate and Matplotlib's colour conversion: a value for which matplotlib.colors.is_color_like reports True must be convertible by the colour conversion routines, and a value the conversion routines reject must not be reported as colour-like.","success_criteria":"for strings of the form produced by np.arange(1000).astype(str), the predicate and the conversion agree, so that either both accept them or both reject them, and the previously supported string colour spellings (named colours, hex, CN cycle references, and grayscale strings) keep working unchanged.","primary_terms":["ValueError","is_color_like","lib/matplotlib/colors.py","matplotlib/matplotlib","matplotlib.colors.is_color_like","to_rgba_array","to_rgba","plt.scatter","set_facecolor","_set_facecolor","Collection.__init__","lib/matplotlib/collections.py"],"search_signals":["Error signature: ValueError","Traceback path: lib/matplotlib/colors.py","Repository: matplotlib/matplotlib","Issue title: ` is_color_like returning erroneous value on strings of integers `.","Symbols: matplotlib.colors.is_color_like, to_rgba_array, to_rgba, plt.scatter, set_facecolor, _set_facecolor, Collection.__init__.","Files: lib/matplotlib/colors.py, lib/matplotlib/collections.py, lib/matplotlib/axes/_axes.py, lib/matplotlib/pyplot.py.","Verbatim error string: ValueError: RGBA values should be within 0-1 range.","Reproduction: c = np.arange(1000).astype(str), plt.scatter(X[:, 0], X[:, 1], c=c), assert all([matplotlib.colors.is_color_like(color) for color in c]).","Environment details quoted in the report: Matplotlib 3.0.2, backend Qt5Agg, Python 3.7.1, numpy 1.15.0, Arch Linux, \"runs without any errors on Windows, Python 3.6, matplotlib 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