Type Casting
- Expr.cast(
- dtype: Boolean | Categorical | Date | Datetime | Decimal | Duration | Enum | Float32 | Float64 | Int8 | Int16 | Int64 | Int32 | Int128 | Null | String | Time | UInt8 | UInt16 | UInt32 | UInt64 | type[Any],
- *,
- strict: bool = True,
- wrap_numerical: bool = False,
- Categories:
type_casting
Cast a value to d different type.
- Parameters:
dtype – The data type to cast to.
strict – If false, invalid casts produce null’s; if true, an excetion is raised.
wrap_numerical – If true, overflowing numbers ara handled; if false, an excetion is raised.
Example:
>>> import tabsdata as td >>> import polars as pl >>> >>> tf: td.TableFrame ... >>> >>> tf = tf.select(td.col("val"), td.col("val").cast(td.Float64)).alias("cast") >>> ┌──────┬──────┐ │ val ┆ cast │ │ --- ┆ --- │ │ i64 ┆ f64 │ ╞══════╪══════╡ │ 1 ┆ 1.0 │ │ 15 ┆ 15.0 │ │ 18 ┆ 18.0 │ │ 60 ┆ 60.0 │ │ 60 ┆ 60.0 │ │ 75 ┆ 75.0 │ │ null ┆ null │ └──────┴──────┘
- ExprStringNameSpace.to_date( ) Expr
- Categories:
type_casting
Convert the string to a date.
- Parameters:
fmt – The date format string (default %Y-%m-%d). See formats.
strict – Whether to parse the date strictly.
Example:
>>> import tabsdata as td >>> >>> tf: td.TableFrame ... >>> >>> tf.select(td.col("a"), td.col("a").str.to_date().alias("to_date")) >>> ┌────────────┬────────────┐ │ a ┆ to_date │ │ --- ┆ --- │ │ str ┆ date │ ╞════════════╪════════════╡ │ 2024-12-13 ┆ 2024-12-13 │ │ 2024-12-15 ┆ 2024-12-15 │ │ null ┆ null │ └────────────┴────────────┘
- ExprStringNameSpace.to_datetime(
- format: str | None = None,
- *,
- time_unit: Literal['ns', 'us', 'ms'] | None = None,
- time_zone: str | None = None,
- strict: bool = True,
- ambiguous: Literal['earliest', 'latest', 'raise', 'null'] | Expr = 'raise',
- Categories:
type_casting
Convert the string to a datetime.
- Parameters:
format –
The datetime format string (default %Y-%m-%d %H:%M:%S). See formats.
time_unit – {None, ‘us’, ‘ns’, ‘ms’} If None (default), it inferred from the format string
time_zone – Time zone for the resulting value.
strict – If the conversion fails an error will be raised.
ambiguous – Policy to apply on ambiguos Datetimes: ‘raise’: saises an error ‘earliest’: use the earliest datetime ‘latest’: use the latest datetime ‘null’: set to null
>>> import tabsdata as td >>> >>> tf: td.TableFrame ... >>> >>> tf.select(td.col("a"), td.col("a").str.to_datetime().alias("to_datetime")) >>> ┌─────────────────────┬─────────────────────┐ │ a ┆ to_datetime │ │ --- ┆ --- │ │ str ┆ datetime[μs] │ ╞═════════════════════╪═════════════════════╡ │ 2024-12-13 08:45:34 ┆ 2024-12-13 08:45:34 │ │ 2024-12-15 18:33:00 ┆ 2024-12-15 18:33:00 │ │ null ┆ null │ └─────────────────────┴─────────────────────┘
- ExprStringNameSpace.to_integer( ) td_expr.Expr
- Categories:
type_casting
Covert a string to integer.
- Parameters:
base – The base of the integer.
strict – If true, raise an error if the string is not a valid integer.
Example:
>>> import tabsdata as td >>> >>> tf: td.TableFrame ... >>> >>> tf.select(td.col("a"), td.col("a") .str.to_integer(strict=False).alias("to_integer")) >>> ┌──────┬────────────┐ │ a ┆ to_integer │ │ --- ┆ --- │ │ str ┆ i64 │ ╞══════╪════════════╡ │ 1 ┆ 1 │ │ 2.2 ┆ null │ │ a ┆ null │ │ null ┆ null │ └──────┴────────────┘
- ExprStringNameSpace.to_time( ) Expr
- Categories:
type_casting
Convert the string to a time.
- Parameters:
fmt –
The time format string (default %H:%M:%S). See formats.
strict – Whether to parse the date strictly.
cache – Whether to cache the date.
Example:
>>> import tabsdata as td >>> >>> tf: td.TableFrame ... >>> >>> tf.select(td.col("a"), td.col("a").str.to_time().alias("to_time")) >>> ┌─────────────────────┬─────────────────────┐ │ a ┆ to_datetime │ │ --- ┆ --- │ │ str ┆ datetime[μs] │ ╞═════════════════════╪═════════════════════╡ │ 2024-12-13 08:45:34 ┆ 2024-12-13 08:45:34 │ │ 2024-12-15 18:33:00 ┆ 2024-12-15 18:33:00 │ │ null ┆ null │ └─────────────────────┴─────────────────────┘