203 lines
7.0 KiB
Python
203 lines
7.0 KiB
Python
from __future__ import annotations
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import operator
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from functools import reduce
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from itertools import chain
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from typing import TYPE_CHECKING
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import duckdb
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from duckdb import CoalesceOperator, Expression
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from duckdb.typing import BIGINT, VARCHAR
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from narwhals._compliant import LazyNamespace, LazyThen, LazyWhen
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from narwhals._duckdb.dataframe import DuckDBLazyFrame
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from narwhals._duckdb.expr import DuckDBExpr
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from narwhals._duckdb.selectors import DuckDBSelectorNamespace
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from narwhals._duckdb.utils import (
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DeferredTimeZone,
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F,
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concat_str,
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lit,
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narwhals_to_native_dtype,
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when,
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)
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from narwhals._expression_parsing import (
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combine_alias_output_names,
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combine_evaluate_output_names,
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)
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from narwhals._utils import Implementation
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if TYPE_CHECKING:
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from collections.abc import Iterable, Sequence
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from narwhals._duckdb.expr import DuckDBWindowInputs
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from narwhals._utils import Version
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from narwhals.typing import ConcatMethod, IntoDType, NonNestedLiteral
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class DuckDBNamespace(
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LazyNamespace[DuckDBLazyFrame, DuckDBExpr, duckdb.DuckDBPyRelation]
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):
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_implementation: Implementation = Implementation.DUCKDB
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def __init__(self, *, version: Version) -> None:
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self._version = version
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@property
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def selectors(self) -> DuckDBSelectorNamespace:
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return DuckDBSelectorNamespace.from_namespace(self)
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@property
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def _expr(self) -> type[DuckDBExpr]:
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return DuckDBExpr
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@property
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def _lazyframe(self) -> type[DuckDBLazyFrame]:
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return DuckDBLazyFrame
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def concat(
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self, items: Iterable[DuckDBLazyFrame], *, how: ConcatMethod
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) -> DuckDBLazyFrame:
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native_items = [item._native_frame for item in items]
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items = list(items)
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first = items[0]
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schema = first.schema
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if how == "vertical" and not all(x.schema == schema for x in items[1:]):
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msg = "inputs should all have the same schema"
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raise TypeError(msg)
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res = reduce(lambda x, y: x.union(y), native_items)
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return first._with_native(res)
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def concat_str(
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self, *exprs: DuckDBExpr, separator: str, ignore_nulls: bool
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) -> DuckDBExpr:
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def func(df: DuckDBLazyFrame) -> list[Expression]:
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cols = list(chain.from_iterable(expr(df) for expr in exprs))
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if not ignore_nulls:
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null_mask_result = reduce(operator.or_, (s.isnull() for s in cols))
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cols_separated = [
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y
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for x in [
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(col.cast(VARCHAR),)
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if i == len(cols) - 1
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else (col.cast(VARCHAR), lit(separator))
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for i, col in enumerate(cols)
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]
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for y in x
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]
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return [when(~null_mask_result, concat_str(*cols_separated))]
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else:
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return [concat_str(*cols, separator=separator)]
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return self._expr(
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call=func,
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evaluate_output_names=combine_evaluate_output_names(*exprs),
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alias_output_names=combine_alias_output_names(*exprs),
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version=self._version,
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)
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def all_horizontal(self, *exprs: DuckDBExpr, ignore_nulls: bool) -> DuckDBExpr:
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def func(cols: Iterable[Expression]) -> Expression:
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it = (
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(CoalesceOperator(expr, lit(True)) for expr in cols) # noqa: FBT003
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if ignore_nulls
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else cols
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)
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return reduce(operator.and_, it)
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return self._expr._from_elementwise_horizontal_op(func, *exprs)
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def any_horizontal(self, *exprs: DuckDBExpr, ignore_nulls: bool) -> DuckDBExpr:
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def func(cols: Iterable[Expression]) -> Expression:
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it = (
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(CoalesceOperator(expr, lit(False)) for expr in cols) # noqa: FBT003
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if ignore_nulls
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else cols
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)
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return reduce(operator.or_, it)
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return self._expr._from_elementwise_horizontal_op(func, *exprs)
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def max_horizontal(self, *exprs: DuckDBExpr) -> DuckDBExpr:
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def func(cols: Iterable[Expression]) -> Expression:
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return F("greatest", *cols)
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return self._expr._from_elementwise_horizontal_op(func, *exprs)
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def min_horizontal(self, *exprs: DuckDBExpr) -> DuckDBExpr:
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def func(cols: Iterable[Expression]) -> Expression:
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return F("least", *cols)
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return self._expr._from_elementwise_horizontal_op(func, *exprs)
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def sum_horizontal(self, *exprs: DuckDBExpr) -> DuckDBExpr:
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def func(cols: Iterable[Expression]) -> Expression:
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return reduce(operator.add, (CoalesceOperator(col, lit(0)) for col in cols))
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return self._expr._from_elementwise_horizontal_op(func, *exprs)
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def mean_horizontal(self, *exprs: DuckDBExpr) -> DuckDBExpr:
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def func(cols: Iterable[Expression]) -> Expression:
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cols = list(cols)
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return reduce(
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operator.add, (CoalesceOperator(col, lit(0)) for col in cols)
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) / reduce(operator.add, (col.isnotnull().cast(BIGINT) for col in cols))
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return self._expr._from_elementwise_horizontal_op(func, *exprs)
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def when(self, predicate: DuckDBExpr) -> DuckDBWhen:
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return DuckDBWhen.from_expr(predicate, context=self)
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def lit(self, value: NonNestedLiteral, dtype: IntoDType | None) -> DuckDBExpr:
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def func(df: DuckDBLazyFrame) -> list[Expression]:
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tz = DeferredTimeZone(df.native)
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if dtype is not None:
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target = narwhals_to_native_dtype(dtype, self._version, tz)
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return [lit(value).cast(target)] # type: ignore[arg-type]
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return [lit(value)]
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return self._expr(
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func,
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evaluate_output_names=lambda _df: ["literal"],
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alias_output_names=None,
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version=self._version,
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)
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def len(self) -> DuckDBExpr:
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def func(_df: DuckDBLazyFrame) -> list[Expression]:
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return [F("count")]
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return self._expr(
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call=func,
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evaluate_output_names=lambda _df: ["len"],
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alias_output_names=None,
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version=self._version,
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)
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def coalesce(self, *exprs: DuckDBExpr) -> DuckDBExpr:
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def func(cols: Iterable[Expression]) -> Expression:
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return CoalesceOperator(*cols)
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return self._expr._from_elementwise_horizontal_op(func, *exprs)
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class DuckDBWhen(LazyWhen["DuckDBLazyFrame", Expression, DuckDBExpr]):
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@property
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def _then(self) -> type[DuckDBThen]:
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return DuckDBThen
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def __call__(self, df: DuckDBLazyFrame) -> Sequence[Expression]:
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self.when = when
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self.lit = lit
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return super().__call__(df)
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def _window_function(
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self, df: DuckDBLazyFrame, window_inputs: DuckDBWindowInputs
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) -> Sequence[Expression]:
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self.when = when
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self.lit = lit
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return super()._window_function(df, window_inputs)
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class DuckDBThen(LazyThen["DuckDBLazyFrame", Expression, DuckDBExpr], DuckDBExpr): ...
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