[C++] Add type inference for boolean values in CSV files

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Reporter: Kouhei Sutou / @kou
Assignee: Antoine Pitrou / @pitrou

PRs and other links:

• GitHub Pull Request #4055

_{Note: This issue was originally created as ARROW-3791. Please see the migration documentation for further details.}

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Antoine Pitrou / @pitrou:
This is handled in ARROW-3722 (see pull request: #2950). You will be able to specify data types for each column, including BooleanType().

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Wes McKinney / @wesm:
He's asking for type inference I think based on the discussion in the PR

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Antoine Pitrou / @pitrou:
Hmm... I don't know if that's a good idea. But I'll reopen the issue and fix the title.

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Wes McKinney / @wesm:
It wouldn't be too harmful if the default recognized T/F values are a conservative set like "true"/"false" or "TRUE"/"FALSE". We might collect data on what other projects do in this regard. I would opt for developer control, though, so this might be something we make configurable (whether type inferences tries boolean by default or not)

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Kouhei Sutou / @kou:
Yes. I want type inference for boolean. Sorry for my ambiguous title.

I think that specifying type explicitly is very useful. But type inference is also useful even if it may choose wrong type because it's convenient. If type inference is failed, we can specify type explicitly. It's convenience than we specify all types explicitly.

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Wes McKinney / @wesm:
Issue resolved by pull request 4055
#4055