pymc-devs/pymc

Replace `assert` checks in `logprob.scan` with real error handling

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#7,780 创建于 2025年5月9日

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 (1 评论) (0 反应) (0 负责人)Python (7,926 star) (1,902 fork)batch import
enhancementshackathonhelp wantedneeds infopytensor

描述

Description

There are two annoying assert checks that I commonly run up against when writing time series models here and here. Other users are hitting them too, see for example here.

It would be much nicer to have a real error message that explains what has gone wrong and why, or at least gives some information about which parts of the graph are going wrong.

I'm not 100% sure how one ends up hitting these asserts, so I tagged this with needs info. It seems to have to do with having multiple outputs from the scan inner function in a custom dist.

贡献者指南

技术栈
python
领域
backenddeveloper experience
议题类型
refactor
难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。
3
预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。
1-3 hours
活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。
fresh
清晰度议题是否清楚说明期望改动、验收标准和下一步。
needs investigation
前置要求
basic Pythonfamiliarity with PyMC
新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。
55
研究方向
Investigate the conditions that trigger the assert checks at pymc/logprob/scan.py lines 115-116. Replace each assert with a meaningful error message (e.g., using raise TypeError or ValueError) that explains the issue and suggests possible fixes. Test the changes by running existing tests and considering edge cases with multiple scan outputs.
Replace `assert` checks in `logprob.scan` with real error handling · pymc-devs/pymc#7780 | Good First Issue