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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Using edgecolors='face' with stackplot causes value error when using plt.legend()","articleBody":"### Bug report\r\n\r\nI was making a stack plot and wanted the edge colors of the plotted lines to be the same as the fill color instead of the default white, so I set edgecolor='face'. This produces a value error when using plt.legend(). Without the legend function, there are no errors and it plots as expected. I tried changing different parameters of the legend() function, but didn't have any success.\r\n\r\n**Code for reproduction**\r\n\r\n```python\r\nimport numpy as np\r\nimport pandas as pd\r\nimport matplotlib.pyplot as plt\r\n# Create a dataset\r\nmy_count = [\r\n    \"France\", \"Australia\", \"Japan\", \"USA\", \"Germany\",\r\n    \"Congo\", \"China\", \"England\", \"Spain\", \"Greece\",\r\n    \"Marocco\", \"South Africa\", \"Indonesia\", \"Peru\", \"Chili\", \"Brazil\"\r\n]\r\ndf = pd.DataFrame(\r\n    {\r\n        \"country\": np.repeat(my_count, 10),\r\n        \"years\": list(range(2000, 2010)) * 16,\r\n        \"value\": np.random.rand(160)\r\n    }\r\n)\r\npivot = df.groupby([\"country\", \"years\"])[\"value\"].sum().unstack(0).cumsum()\r\n# Plot dataset\r\nplt.stackplot(\r\n    pivot.index.values,\r\n    pivot.T.values,\r\n    labels=pivot.columns,\r\n    alpha=0.2,\r\n    edgecolors=\"face\"\r\n)\r\nplt.legend()\r\nplt.show()\r\n```\r\n\r\n**Actual outcome**\r\n\r\n![image](https://user-images.githubusercontent.com/84412599/118715736-96312c00-b7e9-11eb-83f2-4139e7deb5f4.png)\r\nwith the following value error:\r\n\r\n```\r\nValueError: Using a string of single character colors as a color sequence is not supported. The colors can be passed as an explicit list instead.\r\n```\r\n\r\n**Expected outcome**\r\n\r\nThe same graph as above, but with a legend.\r\n\r\n**Matplotlib version**\r\n  * Operating system: Microsoft Windows 10\r\n  * Matplotlib version: 3.4.2 \r\n  * Matplotlib backend: module://ipykernel.pylab.backend_inline \r\n  * Python version: 3.8.5\r\n  * Other libraries: numpy, pandas (to create dataset)\r\n\r\nInstalled matplotlib using 'pip install matplotlib'.\r\n\r\n","author":{"url":"https://github.com/Stratton19","@type":"Person","name":"Stratton19"},"datePublished":"2021-05-18T20:03:44.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/20258/matplotlib/issues/20258"}