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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[ENH]: ticker.EngFormatter: allow offset","articleBody":"### Problem\n\nI want to be able to generate this plot:\r\n\r\n![Screenshot from 2024-06-26 01-11-31](https://github.com/matplotlib/matplotlib/assets/10998835/99cba3bd-0668-4009-a2e5-c4e3485cfd67)\r\n\r\nI managed to create this plot using the following code:\r\n\r\n```python\r\nfrom itertools import count\r\nfrom math import copysign\r\n\r\n# https://pypi.org/project/prefixed/\r\nfrom prefixed import Float\r\n\r\nfrom matplotlib.ticker import ScalarFormatter\r\n\r\nclass FrequencyFormatter(ScalarFormatter):\r\n    def format_data(self, value):\r\n        # Add the Hz suffix\r\n        return '{:H}Hz'.format(Float(value))\r\n    def _set_order_of_magnitude(self):\r\n        super()._set_order_of_magnitude()\r\n        c = abs(self.orderOfMagnitude)\r\n        # Search 0, -3, 3, -6, 6, -9, 9 etc until the best scientifically\r\n        # prefixed oom is found, and then set self.orderOfMagnitude to it\r\n        for sciOom in count(3,3):\r\n            if c \u003c sciOom:\r\n                self.orderOfMagnitude = copysign(sciOom, self.orderOfMagnitude)\r\n                break\r\n\r\n# fig,ax...\r\n\r\nax.yaxis.set_major_formatter(FrequencyFormatter(\r\n    # I'm not necessarily interested in this, but without this,\r\n    # ScalarFormatter.get_offset doesn't use my own .format_data function to\r\n    # format also the offset.\r\n    useMathText=True\r\n))\r\n```\r\n\r\nIt is not ideal because it relies both upon modifying (the private) `_set_order_of_magnitude` method and the external library `prefixed`, which implements something already implemented in the [`EngFormatter`](https://matplotlib.org/stable/api/ticker_api.html#matplotlib.ticker.EngFormatter).\r\n\r\nI'm surprised that [`EngFormatter`](https://matplotlib.org/stable/api/ticker_api.html#matplotlib.ticker.EngFormatter) doesn't handle offsets so smartly like `ScalarFormatter`...\r\n\r\nWhere do you think this kind of enhancement would fit most? In `EngFormatter` with an additional `__init__` argument? Or in a new formatter?\n\n### Proposed solution\n\nSort of proposed above...","author":{"url":"https://github.com/doronbehar","@type":"Person","name":"doronbehar"},"datePublished":"2024-06-25T23:10:34.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":5},"url":"https://github.com/28463/matplotlib/issues/28463"}