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Add 2d constructor #208

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Merged
merged 4 commits into from
Aug 1, 2023
Merged

Add 2d constructor #208

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6f244b6
add 2d constructor
MarcoGorelli Jul 24, 2023
2e56e3a
add names and dtypes params
MarcoGorelli Jul 24, 2023
765eb20
add column from 1d array too
MarcoGorelli Jul 25, 2023
c106392
add note about casting
MarcoGorelli Jul 28, 2023
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14 changes: 14 additions & 0 deletions spec/API_specification/dataframe_api/__init__.py
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Expand Up @@ -96,6 +96,20 @@ def dataframe_from_dict(data: Mapping[str, Column[Any]]) -> DataFrame:
"""
...

def dataframe_from_2d_array(array: Any) -> DataFrame:
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This should have *, names: list[str] I think, with the length of the list matching the number of columns?

Also a dtype keyword, because we don't really want to get in the business of inferring it (going from array.dtype to a dtype in this namespace is nontrivial; much easier for the caller who has the array namespace at hand).

"""
Construct DataFrame from 2D array.

See `column_from_sequece` for related 1D function.
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typo in sequence

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More importantly, I foresee a column_from_1d_array request, because a 1-D array is not a sequence.

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I wasn't aware, thanks

just for my understanding, what makes it not a sequence? from the docs https://docs.python.org/3/glossary.html#term-sequence :

An iterable which supports efficient element access using integer indices via the getitem() special method and defines a len() method that returns the length of the sequence

, don't arrays meet the requirement?

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See data-apis/array-api#481 for len(). A second issue is that iterating over it is going to return 0-D arrays of the dtype of the input array, not Python scalars.

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Are arrays iterable per the array API? I would strongly prefer to differentiate array handling vs iterable handling since you can often handle array zero copy or at least in very efficient ways relative to iterables.

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sure, I've added column from 1d too


Only Array-API-compliant 2D arrays are supported.

Returns
-------
DataFrame
"""
...

class null:
"""
A `null` object to represent missing data.
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