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Polars · Module
df.limit
DataFrame.limit(n) returns the first n rows as a DataFrame, defaulting to five rows. A negative n returns all rows except the last abs(n) rows.
How it works
Call limit on a DataFrame to produce a DataFrame containing a bounded prefix of its rows. A positive n keeps the first n rows, while a negative n removes that many rows from the end instead; the method is equivalent to head.
Syntax
DataFrame.limit(n: int = 5) -> DataFrameParameters
| Name | Type | Description |
|---|---|---|
n | int = 5 | Number of rows to return. Negative values return all rows except the last abs(n) rows. |
Returns
DataFrame
Key points
- Use
limit(n)to keep a leading slice of the DataFrame. limitandheadare equivalent DataFrame operations.- The
nargument controls the requested row count. - A negative
nexcludesabs(n)rows from the end. - The default call requests five rows and returns another DataFrame.
Common mistakes
- Negative values do not select rows from the end; they exclude that many rows from the DataFrame's tail.
Example: Limit rows
import polars as pl
df = pl.DataFrame({"value": [10, 20, 30, 40, 50]})
print(df.limit(3))
print(df.limit(-2))Returns a new DataFrame containing the first three rows, then all rows except the final two.
When to use it
Keep only an initial row window
Bounding intermediate results
Exclude the final rows with a negative limit
Dropping a known tail
Interview questions
QWhat does DataFrame.limit return, and what is its default?
DataFrame.limit(n) returns the first n rows as a DataFrame, with n defaulting to 5. It is an alias for DataFrame.head().
Follow-up: What does limit(-n) do? It returns every row except the last abs(n) rows.
QWhat is the parameter and return type of limit?
The method accepts one integer parameter, n, which specifies the number of rows to return. The result preserves the DataFrame form rather than returning a scalar or a list.
Follow-up: How would you inspect the result without changing the original object? Assign or print the returned DataFrame; the documented operation returns a DataFrame.
QHow does negative n differ from positive n?
A positive limit selects a prefix of the DataFrame. A negative limit instead returns all rows other than the specified number at the end.
Follow-up: What related API provides the same behavior? DataFrame.head() is the documented alias.
Related
DataFrame.head