René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Doc]: `contour` and `contourf` levels default not specified","articleBody":"### Documentation Link\n\nhttps://matplotlib.org/devdocs/api/_as_gen/matplotlib.pyplot.contourf.html\n\n### Problem\n\n`levels` is specified to be optional but the default value is not specified.\n\n\n\n\n\n\n### Suggested improvement\n\nDigging into the code, it seems that [`_process_contour_level_args`](https://github.com/matplotlib/matplotlib/blob/ebf9b14f7f41029e2c61dd09cc37dae98a9bc10d/lib/matplotlib/contour.py#L1011C9-L1011C36) is responsible? It calls `_ensure_locator_exists` :\n\n\nhttps://github.com/matplotlib/matplotlib/blob/ebf9b14f7f41029e2c61dd09cc37dae98a9bc10d/lib/matplotlib/contour.py#L957-L975\n\nSo does this mean that `levels=1` gets passed as `MaxNLocator(n_bins=2)` which gives max `n_bins + 1` (3) levels?\n\nAlso in `levels` it is specified:\n\n\u003e If an int n, use [MaxNLocator](https://matplotlib.org/devdocs/api/ticker_api.html#matplotlib.ticker.MaxNLocator), which tries to automatically choose no more than n+1 \"nice\" contour levels between minimum and maximum numeric values of Z.\n\nBut considering we pass `MaxNLocator(N+1)`, is it n+1 or n+2 ?","author":{"url":"https://github.com/lucyleeow","@type":"Person","name":"lucyleeow"},"datePublished":"2026-01-19T11:17:01.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":8},"url":"https://github.com/30996/matplotlib/issues/30996"}