Format a string using the given arguments.
Parameters:
| Name | Type | Description | Default |
f_string | str | | required |
*args | Expression | str | The arguments to format the string with. | () |
Returns:
| Name | Type | Description |
Expression | Expression | A string expression with the formatted result. |
Examples:
| >>> import daft
>>> from daft.functions import format
>>> from daft import col
>>> df = daft.from_pydict({"first_name": ["Alice", "Bob"], "last_name": ["Smith", "Jones"]})
>>> df = df.with_column("greeting", format("Hello {} {}", col("first_name"), "last_name"))
>>> df.show()
|
╭────────────┬───────────┬───────────────────╮
│ first_name ┆ last_name ┆ greeting │
│ --- ┆ --- ┆ --- │
│ String ┆ String ┆ String │
╞════════════╪═══════════╪═══════════════════╡
│ Alice ┆ Smith ┆ Hello Alice Smith │
├╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ Bob ┆ Jones ┆ Hello Bob Jones │
╰────────────┴───────────┴───────────────────╯
(Showing first 2 of 2 rows)
Source code in daft/functions/str.py
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150 | def format(f_string: str, *args: Expression | str) -> Expression:
"""Format a string using the given arguments.
Args:
f_string: The format string.
*args: The arguments to format the string with.
Returns:
Expression: A string expression with the formatted result.
Examples:
>>> import daft
>>> from daft.functions import format
>>> from daft import col
>>> df = daft.from_pydict({"first_name": ["Alice", "Bob"], "last_name": ["Smith", "Jones"]})
>>> df = df.with_column("greeting", format("Hello {} {}", col("first_name"), "last_name"))
>>> df.show()
╭────────────┬───────────┬───────────────────╮
│ first_name ┆ last_name ┆ greeting │
│ --- ┆ --- ┆ --- │
│ String ┆ String ┆ String │
╞════════════╪═══════════╪═══════════════════╡
│ Alice ┆ Smith ┆ Hello Alice Smith │
├╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ Bob ┆ Jones ┆ Hello Bob Jones │
╰────────────┴───────────┴───────────────────╯
<BLANKLINE>
(Showing first 2 of 2 rows)
"""
if f_string.count("{}") != len(args):
raise ValueError(
f"Format string {f_string} has {f_string.count('{}')} placeholders but {len(args)} arguments were provided"
)
parts = f_string.split("{}")
exprs = []
for part, arg in zip(parts, args):
if part:
exprs.append(lit(part))
if isinstance(arg, str):
exprs.append(col(arg))
else:
exprs.append(arg)
if parts[-1]:
exprs.append(lit(parts[-1]))
if not exprs:
return lit("")
result = exprs[0]
for expr in exprs[1:]:
result = result + expr
return result
|