18 lines
456 B
Markdown
18 lines
456 B
Markdown
---
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title: find_index
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tags: list,beginner
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---
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Returns the index of the first element in the provided list that satisfies the provided testing function.
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- Use list comprehension, `enumerate()` and `next()` to return the index of the first element in `lst` for which `fn` returns `True`.
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```py
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def find_index(lst, fn):
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return next(i for i, x in enumerate(lst) if fn(x))
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```
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```py
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find_index([1, 2, 3, 4], lambda n: n % 2 == 1) # 0
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```
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