diff --git a/python/datafusion/functions.py b/python/datafusion/functions.py index fd116254b..bb6afdd7f 100644 --- a/python/datafusion/functions.py +++ b/python/datafusion/functions.py @@ -295,7 +295,15 @@ def isnan(expr: Expr) -> Expr: - """Returns true if a given number is +NaN or -NaN otherwise returns false.""" + """Returns true if a given number is +NaN or -NaN otherwise returns false. + + Examples: + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [1.0, np.nan]}) + >>> result = df.select(dfn.functions.isnan(dfn.col("a")).alias("isnan")) + >>> result.collect_column("isnan")[1].as_py() + True + """ return Expr(f.isnan(expr.expr)) @@ -303,29 +311,65 @@ def nullif(expr1: Expr, expr2: Expr) -> Expr: """Returns NULL if expr1 equals expr2; otherwise it returns expr1. This can be used to perform the inverse operation of the COALESCE expression. + + Examples: + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [1, 2], "b": [1, 3]}) + >>> result = df.select( + ... dfn.functions.nullif(dfn.col("a"), dfn.col("b")).alias("nullif")) + >>> result.collect_column("nullif").to_pylist() + [None, 2] """ return Expr(f.nullif(expr1.expr, expr2.expr)) def encode(expr: Expr, encoding: Expr) -> Expr: - """Encode the ``input``, using the ``encoding``. encoding can be base64 or hex.""" + """Encode the ``input``, using the ``encoding``. encoding can be base64 or hex. + + Examples: + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": ["hello"]}) + >>> result = df.select( + ... dfn.functions.encode(dfn.col("a"), dfn.lit("base64")).alias("enc")) + >>> result.collect_column("enc")[0].as_py() + 'aGVsbG8' + """ return Expr(f.encode(expr.expr, encoding.expr)) def decode(expr: Expr, encoding: Expr) -> Expr: - """Decode the ``input``, using the ``encoding``. encoding can be base64 or hex.""" + """Decode the ``input``, using the ``encoding``. encoding can be base64 or hex. + + Examples: + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": ["aGVsbG8="]}) + >>> result = df.select( + ... dfn.functions.decode(dfn.col("a"), dfn.lit("base64")).alias("dec")) + >>> result.collect_column("dec")[0].as_py() + b'hello' + """ return Expr(f.decode(expr.expr, encoding.expr)) def array_to_string(expr: Expr, delimiter: Expr) -> Expr: - """Converts each element to its text representation.""" + """Converts each element to its text representation. + + Examples: + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [[1, 2, 3]]}) + >>> result = df.select( + ... dfn.functions.array_to_string(dfn.col("a"), dfn.lit(",")).alias("s")) + >>> result.collect_column("s")[0].as_py() + '1,2,3' + """ return Expr(f.array_to_string(expr.expr, delimiter.expr.cast(pa.string()))) def array_join(expr: Expr, delimiter: Expr) -> Expr: """Converts each element to its text representation. - This is an alias for :py:func:`array_to_string`. + See Also: + This is an alias for :py:func:`array_to_string`. """ return array_to_string(expr, delimiter) @@ -333,7 +377,8 @@ def array_join(expr: Expr, delimiter: Expr) -> Expr: def list_to_string(expr: Expr, delimiter: Expr) -> Expr: """Converts each element to its text representation. - This is an alias for :py:func:`array_to_string`. + See Also: + This is an alias for :py:func:`array_to_string`. """ return array_to_string(expr, delimiter) @@ -342,12 +387,27 @@ def list_join(expr: Expr, delimiter: Expr) -> Expr: """Converts each element to its text representation. This is an alias for :py:func:`array_to_string`. + + See Also: + This is an alias for :py:func:`array_to_string`. """ return array_to_string(expr, delimiter) def in_list(arg: Expr, values: list[Expr], negated: bool = False) -> Expr: - """Returns whether the argument is contained within the list ``values``.""" + """Returns whether the argument is contained within the list ``values``. + + Examples: + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [1, 2, 3]}) + >>> result = df.select( + ... dfn.functions.in_list( + ... dfn.col("a"), [dfn.lit(1), dfn.lit(3)] + ... ).alias("in") + ... ) + >>> result.collect_column("in").to_pylist() + [True, False, True] + """ values = [v.expr for v in values] return Expr(f.in_list(arg.expr, values, negated)) @@ -357,6 +417,14 @@ def digest(value: Expr, method: Expr) -> Expr: Standard algorithms are md5, sha224, sha256, sha384, sha512, blake2s, blake2b, and blake3. + + Examples: + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": ["hello"]}) + >>> result = df.select( + ... dfn.functions.digest(dfn.col("a"), dfn.lit("md5")).alias("d")) + >>> len(result.collect_column("d")[0].as_py()) > 0 + True """ return Expr(f.digest(value.expr, method.expr)) @@ -365,6 +433,15 @@ def concat(*args: Expr) -> Expr: """Concatenates the text representations of all the arguments. NULL arguments are ignored. + + Examples: + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": ["hello"], "b": [" world"]}) + >>> result = df.select( + ... dfn.functions.concat(dfn.col("a"), dfn.col("b")).alias("c") + ... ) + >>> result.collect_column("c")[0].as_py() + 'hello world' """ args = [arg.expr for arg in args] return Expr(f.concat(args)) @@ -374,13 +451,27 @@ def concat_ws(separator: str, *args: Expr) -> Expr: """Concatenates the list ``args`` with the separator. ``NULL`` arguments are ignored. ``separator`` should not be ``NULL``. + + Examples: + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": ["hello"], "b": ["world"]}) + >>> result = df.select( + ... dfn.functions.concat_ws("-", dfn.col("a"), dfn.col("b")).alias("c")) + >>> result.collect_column("c")[0].as_py() + 'hello-world' """ args = [arg.expr for arg in args] return Expr(f.concat_ws(separator, args)) def order_by(expr: Expr, ascending: bool = True, nulls_first: bool = True) -> SortExpr: - """Creates a new sort expression.""" + """Creates a new sort expression. + + Examples: + >>> sort_expr = dfn.functions.order_by(dfn.col("a"), ascending=False) + >>> sort_expr.ascending() + False + """ return SortExpr(expr, ascending=ascending, nulls_first=nulls_first) @@ -392,14 +483,26 @@ def alias(expr: Expr, name: str, metadata: dict[str, str] | None = None) -> Expr name: The alias name metadata: Optional metadata to attach to the column - Returns: - An expression with the given alias + Examples: + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [1, 2]}) + >>> df.select( + ... dfn.functions.alias(dfn.col("a"), "b") + ... ).collect_column("b")[0].as_py() + 1 """ return Expr(f.alias(expr.expr, name, metadata)) def col(name: str) -> Expr: - """Creates a column reference expression.""" + """Creates a column reference expression. + + Examples: + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [1, 2, 3]}) + >>> df.select(dfn.functions.col("a")).collect_column("a")[0].as_py() + 1 + """ return Expr(f.col(name)) @@ -413,6 +516,13 @@ def count_star(filter: Expr | None = None) -> Expr: Args: filter: If provided, only count rows for which the filter is True + + Examples: + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [1, 2, 3]}) + >>> result = df.aggregate([], [dfn.functions.count_star().alias("cnt")]) + >>> result.collect_column("cnt")[0].as_py() + 3 """ return count(Expr.literal(1), filter=filter) @@ -423,6 +533,15 @@ def case(expr: Expr) -> CaseBuilder: Create a :py:class:`~datafusion.expr.CaseBuilder` to match cases for the expression ``expr``. See :py:class:`~datafusion.expr.CaseBuilder` for detailed usage. + + Examples: + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [1, 2, 3]}) + >>> result = df.select( + ... dfn.functions.case(dfn.col("a")).when(dfn.lit(1), + ... dfn.lit("one")).otherwise(dfn.lit("other")).alias("c")) + >>> result.collect_column("c")[0].as_py() + 'one' """ return CaseBuilder(f.case(expr.expr)) @@ -433,6 +552,15 @@ def when(when: Expr, then: Expr) -> CaseBuilder: Create a :py:class:`~datafusion.expr.CaseBuilder` to match cases for the expression ``expr``. See :py:class:`~datafusion.expr.CaseBuilder` for detailed usage. + + Examples: + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [1, 2, 3]}) + >>> result = df.select( + ... dfn.functions.when(dfn.col("a") > dfn.lit(2), + ... dfn.lit("big")).otherwise(dfn.lit("small")).alias("c")) + >>> result.collect_column("c")[2].as_py() + 'big' """ return CaseBuilder(f.when(when.expr, then.expr)) @@ -496,12 +624,11 @@ def acos(arg: Expr) -> Expr: """Returns the arc cosine or inverse cosine of a number. Examples: - --------- - >>> ctx = dfn.SessionContext() - >>> df = ctx.from_pydict({"a": [1.0]}) - >>> result = df.select(dfn.functions.acos(dfn.col("a")).alias("acos")) - >>> result.collect_column("acos")[0].as_py() - 0.0 + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [1.0]}) + >>> result = df.select(dfn.functions.acos(dfn.col("a")).alias("acos")) + >>> result.collect_column("acos")[0].as_py() + 0.0 """ return Expr(f.acos(arg.expr)) @@ -510,12 +637,11 @@ def acosh(arg: Expr) -> Expr: """Returns inverse hyperbolic cosine. Examples: - --------- - >>> ctx = dfn.SessionContext() - >>> df = ctx.from_pydict({"a": [1.0]}) - >>> result = df.select(dfn.functions.acosh(dfn.col("a")).alias("acosh")) - >>> result.collect_column("acosh")[0].as_py() - 0.0 + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [1.0]}) + >>> result = df.select(dfn.functions.acosh(dfn.col("a")).alias("acosh")) + >>> result.collect_column("acosh")[0].as_py() + 0.0 """ return Expr(f.acosh(arg.expr)) @@ -529,12 +655,11 @@ def asin(arg: Expr) -> Expr: """Returns the arc sine or inverse sine of a number. Examples: - --------- - >>> ctx = dfn.SessionContext() - >>> df = ctx.from_pydict({"a": [0.0]}) - >>> result = df.select(dfn.functions.asin(dfn.col("a")).alias("asin")) - >>> result.collect_column("asin")[0].as_py() - 0.0 + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [0.0]}) + >>> result = df.select(dfn.functions.asin(dfn.col("a")).alias("asin")) + >>> result.collect_column("asin")[0].as_py() + 0.0 """ return Expr(f.asin(arg.expr)) @@ -543,12 +668,11 @@ def asinh(arg: Expr) -> Expr: """Returns inverse hyperbolic sine. Examples: - --------- - >>> ctx = dfn.SessionContext() - >>> df = ctx.from_pydict({"a": [0.0]}) - >>> result = df.select(dfn.functions.asinh(dfn.col("a")).alias("asinh")) - >>> result.collect_column("asinh")[0].as_py() - 0.0 + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [0.0]}) + >>> result = df.select(dfn.functions.asinh(dfn.col("a")).alias("asinh")) + >>> result.collect_column("asinh")[0].as_py() + 0.0 """ return Expr(f.asinh(arg.expr)) @@ -557,12 +681,11 @@ def atan(arg: Expr) -> Expr: """Returns inverse tangent of a number. Examples: - --------- - >>> ctx = dfn.SessionContext() - >>> df = ctx.from_pydict({"a": [0.0]}) - >>> result = df.select(dfn.functions.atan(dfn.col("a")).alias("atan")) - >>> result.collect_column("atan")[0].as_py() - 0.0 + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [0.0]}) + >>> result = df.select(dfn.functions.atan(dfn.col("a")).alias("atan")) + >>> result.collect_column("atan")[0].as_py() + 0.0 """ return Expr(f.atan(arg.expr)) @@ -571,12 +694,11 @@ def atanh(arg: Expr) -> Expr: """Returns inverse hyperbolic tangent. Examples: - --------- - >>> ctx = dfn.SessionContext() - >>> df = ctx.from_pydict({"a": [0.0]}) - >>> result = df.select(dfn.functions.atanh(dfn.col("a")).alias("atanh")) - >>> result.collect_column("atanh")[0].as_py() - 0.0 + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [0.0]}) + >>> result = df.select(dfn.functions.atanh(dfn.col("a")).alias("atanh")) + >>> result.collect_column("atanh")[0].as_py() + 0.0 """ return Expr(f.atanh(arg.expr)) @@ -585,13 +707,12 @@ def atan2(y: Expr, x: Expr) -> Expr: """Returns inverse tangent of a division given in the argument. Examples: - --------- - >>> ctx = dfn.SessionContext() - >>> df = ctx.from_pydict({"y": [0.0], "x": [1.0]}) - >>> result = df.select( - ... dfn.functions.atan2(dfn.col("y"), dfn.col("x")).alias("atan2")) - >>> result.collect_column("atan2")[0].as_py() - 0.0 + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"y": [0.0], "x": [1.0]}) + >>> result = df.select( + ... dfn.functions.atan2(dfn.col("y"), dfn.col("x")).alias("atan2")) + >>> result.collect_column("atan2")[0].as_py() + 0.0 """ return Expr(f.atan2(y.expr, x.expr)) @@ -646,12 +767,11 @@ def cos(arg: Expr) -> Expr: """Returns the cosine of the argument. Examples: - --------- - >>> ctx = dfn.SessionContext() - >>> df = ctx.from_pydict({"a": [0,-1,1]}) - >>> cos_df = df.select(dfn.functions.cos(dfn.col("a")).alias("cos")) - >>> cos_df.collect_column("cos")[0].as_py() - 1.0 + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [0,-1,1]}) + >>> cos_df = df.select(dfn.functions.cos(dfn.col("a")).alias("cos")) + >>> cos_df.collect_column("cos")[0].as_py() + 1.0 """ return Expr(f.cos(arg.expr)) @@ -660,12 +780,11 @@ def cosh(arg: Expr) -> Expr: """Returns the hyperbolic cosine of the argument. Examples: - --------- - >>> ctx = dfn.SessionContext() - >>> df = ctx.from_pydict({"a": [0,-1,1]}) - >>> cosh_df = df.select(dfn.functions.cosh(dfn.col("a")).alias("cosh")) - >>> cosh_df.collect_column("cosh")[0].as_py() - 1.0 + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [0,-1,1]}) + >>> cosh_df = df.select(dfn.functions.cosh(dfn.col("a")).alias("cosh")) + >>> cosh_df.collect_column("cosh")[0].as_py() + 1.0 """ return Expr(f.cosh(arg.expr)) @@ -674,18 +793,17 @@ def cot(arg: Expr) -> Expr: """Returns the cotangent of the argument. Examples: - --------- - >>> from math import pi - >>> ctx = dfn.SessionContext() - >>> df = ctx.from_pydict({"a": [pi / 4]}) - >>> import builtins - >>> result = df.select( - ... dfn.functions.cot(dfn.col("a")).alias("cot") - ... ) - >>> builtins.round( - ... result.collect_column("cot")[0].as_py(), 1 - ... ) - 1.0 + >>> from math import pi + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [pi / 4]}) + >>> import builtins + >>> result = df.select( + ... dfn.functions.cot(dfn.col("a")).alias("cot") + ... ) + >>> builtins.round( + ... result.collect_column("cot")[0].as_py(), 1 + ... ) + 1.0 """ return Expr(f.cot(arg.expr)) @@ -694,13 +812,12 @@ def degrees(arg: Expr) -> Expr: """Converts the argument from radians to degrees. Examples: - --------- - >>> from math import pi - >>> ctx = dfn.SessionContext() - >>> df = ctx.from_pydict({"a": [0,pi,2*pi]}) - >>> deg_df = df.select(dfn.functions.degrees(dfn.col("a")).alias("deg")) - >>> deg_df.collect_column("deg")[2].as_py() - 360.0 + >>> from math import pi + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [0,pi,2*pi]}) + >>> deg_df = df.select(dfn.functions.degrees(dfn.col("a")).alias("deg")) + >>> deg_df.collect_column("deg")[2].as_py() + 360.0 """ return Expr(f.degrees(arg.expr)) @@ -882,18 +999,17 @@ def radians(arg: Expr) -> Expr: """Converts the argument from degrees to radians. Examples: - --------- - >>> from math import pi - >>> ctx = dfn.SessionContext() - >>> df = ctx.from_pydict({"a": [180.0]}) - >>> import builtins - >>> result = df.select( - ... dfn.functions.radians(dfn.col("a")).alias("rad") - ... ) - >>> builtins.round( - ... result.collect_column("rad")[0].as_py(), 6 - ... ) - 3.141593 + >>> from math import pi + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [180.0]}) + >>> import builtins + >>> result = df.select( + ... dfn.functions.radians(dfn.col("a")).alias("rad") + ... ) + >>> builtins.round( + ... result.collect_column("rad")[0].as_py(), 6 + ... ) + 3.141593 """ return Expr(f.radians(arg.expr)) @@ -1058,12 +1174,11 @@ def sin(arg: Expr) -> Expr: """Returns the sine of the argument. Examples: - --------- - >>> ctx = dfn.SessionContext() - >>> df = ctx.from_pydict({"a": [0.0]}) - >>> result = df.select(dfn.functions.sin(dfn.col("a")).alias("sin")) - >>> result.collect_column("sin")[0].as_py() - 0.0 + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [0.0]}) + >>> result = df.select(dfn.functions.sin(dfn.col("a")).alias("sin")) + >>> result.collect_column("sin")[0].as_py() + 0.0 """ return Expr(f.sin(arg.expr)) @@ -1072,12 +1187,11 @@ def sinh(arg: Expr) -> Expr: """Returns the hyperbolic sine of the argument. Examples: - --------- - >>> ctx = dfn.SessionContext() - >>> df = ctx.from_pydict({"a": [0.0]}) - >>> result = df.select(dfn.functions.sinh(dfn.col("a")).alias("sinh")) - >>> result.collect_column("sinh")[0].as_py() - 0.0 + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [0.0]}) + >>> result = df.select(dfn.functions.sinh(dfn.col("a")).alias("sinh")) + >>> result.collect_column("sinh")[0].as_py() + 0.0 """ return Expr(f.sinh(arg.expr)) @@ -1129,12 +1243,11 @@ def tan(arg: Expr) -> Expr: """Returns the tangent of the argument. Examples: - --------- - >>> ctx = dfn.SessionContext() - >>> df = ctx.from_pydict({"a": [0.0]}) - >>> result = df.select(dfn.functions.tan(dfn.col("a")).alias("tan")) - >>> result.collect_column("tan")[0].as_py() - 0.0 + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [0.0]}) + >>> result = df.select(dfn.functions.tan(dfn.col("a")).alias("tan")) + >>> result.collect_column("tan")[0].as_py() + 0.0 """ return Expr(f.tan(arg.expr)) @@ -1143,12 +1256,11 @@ def tanh(arg: Expr) -> Expr: """Returns the hyperbolic tangent of the argument. Examples: - --------- - >>> ctx = dfn.SessionContext() - >>> df = ctx.from_pydict({"a": [0.0]}) - >>> result = df.select(dfn.functions.tanh(dfn.col("a")).alias("tanh")) - >>> result.collect_column("tanh")[0].as_py() - 0.0 + >>> ctx = dfn.SessionContext() + >>> df = ctx.from_pydict({"a": [0.0]}) + >>> result = df.select(dfn.functions.tanh(dfn.col("a")).alias("tanh")) + >>> result.collect_column("tanh")[0].as_py() + 0.0 """ return Expr(f.tanh(arg.expr))