René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: PDF Type 42 output regression in 3.11: excessive font embedding and fl rendered as a ligature","articleBody":"### Bug summary\n\nAfter upgrading from Matplotlib 3.9.4 to 3.11.0, PDF files generated with the default\n`DejaVu Sans` font and `pdf.fonttype = 42` became significantly larger.\n\nAdditionally, words containing the character sequence `fl` (for example, `Ecoflow`)\nare rendered with a ligature, while this did not happen with Matplotlib 3.9.x.\n\nThe same code, data, and font are used in both versions.\n\n### Expected behavior\n\n- PDF size should remain similar to Matplotlib 3.9.4.\n- The text `Ecoflow` should be rendered as separate `f` and `l` glyphs.\n- Only the required font subset should be embedded.\n\n### Actual behavior\n\nWith Matplotlib 3.11.0:\n\n- PDF size increases.\n- The sequence `fl` is rendered as a ligature.\n- The issue only occurs when using `pdf.fonttype = 42`.\n\n**Working configuration:**\n\n- Python: **3.9.13**\n- Matplotlib: **3.9.4**\n\n**Affected configuration:**\n\n- Python: **3.14.6**\n- Matplotlib: **3.11.0**\n\n\n### Code for reproduction\n\n```Python\nimport matplotlib\nfrom matplotlib.figure import Figure\n\nmatplotlib.rcParams['pdf.fonttype'] = 42\nmatplotlib.rcParams['pdf.compression'] = 9\n\nfig = Figure()\nax = fig.subplots()\n\nax.set_title(\"Ecoflow\")\n\nfig.savefig(\"ligature-bug.pdf\")\n```\n\n### Actual outcome\n\n\u003cimg width=\"882\" height=\"188\" alt=\"Image\" src=\"https://github.com/user-attachments/assets/a7464948-1d21-49b7-a625-c9d753af4ea8\" /\u003e\n\n### Expected outcome\n\n\u003cimg width=\"900\" height=\"224\" alt=\"Image\" src=\"https://github.com/user-attachments/assets/2fbf7bca-0863-491e-bdd0-c5e7bd3dc3d8\" /\u003e\n\n### Additional information\n\n_No response_\n\n### Operating system\n\nDebian\n\n### Matplotlib Version\n\n3.11.0\n\n### Matplotlib Backend\n\nagg\n\n### Python version\n\nPython 3.14.6\n\n### Jupyter version\n\n_No response_\n\n### Installation\n\npip","author":{"url":"https://github.com/smirnovhub","@type":"Person","name":"smirnovhub"},"datePublished":"2026-06-26T20:55:37.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":5},"url":"https://github.com/31955/matplotlib/issues/31955"}