Update _builder.pyx

[mlsquareup]

Exponentiation appears to cause type conversion to double in some instances.

Proposed changes

Same issue as shown in #534. I cannot deploy causalml models in SageMaker because I see same error, and also on my M1 laptop.

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Further comments

Small change to ensure any type conversion due to exponentiation is undone.

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[mlsquareup]

I think the exponentiation results in type conversion to float. This is causing me issues in the installation.

 Error compiling Cython file:
      ------------------------------------------------------------
      ...
      
              # Initial capacity
              cdef int init_capacity
      
              if tree.max_depth <= 10:
                  init_capacity = (2 ** (tree.max_depth + 1)) - 1
                                                              ^
      ------------------------------------------------------------
      
      causalml/inference/tree/causal/_builder.pyx:61:56: Cannot assign type 'double' to 'int'

[eugeneyarovoi]

That's weird though. The rule in Python is that integer exponentiation results in an integer, how is it giving a double here? Does CPython have different rules?

[leoifood]

This solved my problems installing in python 3.8

[jeongyoonlee]

Thanks for your contribution, @mlsquareup. Currently, pytest builds are failing (e.g., py3.8). Can you see if you can fix it?

[mlsquareup]

Thanks for your contribution, @mlsquareup. Currently, pytest builds are failing (e.g., py3.8). Can you see if you can fix it?

Probably just missing duecredit package. Let me check.

[mlsquareup]

Let's see if this build works. Seems like we were missing one package for testing.

[bsaunders27]

Fun fact, apparently duecredit isn't actually necessary (see screenshot of successful build. Looks like the issue is with the cached version of Cython being 3.0.0 which has some integration issues (solved in #640 ).

[eugeneyarovoi]

@bsaunders27 I think your PR is a more comprehensive version of what @mlsquareup was trying to do here. Maybe you can just push your changes forward and we can close this?

[jeongyoonlee]

Hi @mlsquareup. Thanks for your contribution. As the issue has been in #640 and #641, we will close your PR.
We are looking forward to your contribution.