Replace list+ndarray concatenation with numpy operations in tutorials

[Copilot]

The pattern [-1] + revenue_locations mixes Python list concatenation with numpy arrays, creating type inconsistency and obscuring intent.

Changes

• Replaced [-1] + array_name with np.insert(array_name, 0, -1) in both tutorials
• Updated 4 instances in hillstrom.rst
• Updated 4 instances in oregon.rst

Example

# Before
locations=[-1] + revenue_locations  # Returns list

# After  
locations=np.insert(revenue_locations, 0, -1)  # Returns ndarray

Both produce functionally equivalent results, but the numpy operation maintains type consistency and clearly expresses the intent to prepend -1 to the array.

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[Copilot]

Pull request overview

This PR updates the documentation tutorials to avoid mixing Python list concatenation with NumPy arrays when prepending -1 to location arrays, keeping types consistent with the library’s locations: np.ndarray API expectations.

Changes:

• Replaced [-1] + <numpy_array> with np.insert(<array>, 0, -1) in the Hillstrom tutorial.
• Replaced [-1] + <numpy_array> with np.insert(<array>, 0, -1) in the Oregon tutorial.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
docs/source/tutorials/hillstrom.rst	Uses np.insert(..., 0, -1) for predict_pte(..., locations=...) to keep locations as an ndarray.
docs/source/tutorials/oregon.rst	Uses np.insert(..., 0, -1) for predict_lpte(..., locations=...) in both costs and visits sections to keep locations as an ndarray.

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