Nagato-Yuzuru commented on code in PR #22702:
URL: https://github.com/apache/datafusion/pull/22702#discussion_r3348586235
##########
datafusion/core/src/dataframe/mod.rs:
##########
@@ -2527,6 +2528,78 @@ impl DataFrame {
.collect()
}
+ /// Fill NaN values in specified columns with a given value
+ /// If no columns are specified (empty vector), applies to all columns
+ /// Only fills if the value can be cast to the column's type
+ ///
+ /// # Arguments
+ /// * `value` - Value to fill NaNs with
+ /// * `columns` - List of column names to fill. If empty, fills all
columns.
+ ///
+ /// # Example
+ /// ```
+ /// # use datafusion::prelude::*;
+ /// # use datafusion::error::Result;
+ /// # use datafusion_common::ScalarValue;
+ /// # #[tokio::main]
+ /// # async fn main() -> Result<()> {
+ /// let ctx = SessionContext::new();
+ /// let df = ctx
+ /// .read_csv("tests/data/example.csv", CsvReadOptions::new())
+ /// .await?;
+ /// // Fill NaN in only columns "a" and "c":
+ /// let df = df.fill_nan(ScalarValue::from(0.0), vec!["a".to_owned(),
"c".to_owned()])?;
+ /// // Fill NaN across all columns:
+ /// let df = df.fill_nan(ScalarValue::from(0.0), vec![])?;
+ /// # Ok(())
+ /// # }
+ /// ```
+ #[expect(clippy::needless_pass_by_value)]
+ pub fn fill_nan(
+ &self,
+ value: ScalarValue,
+ columns: Vec<String>,
+ ) -> Result<DataFrame> {
Review Comment:
Update: I use `&[&str]` instead of `&[impl Into<Column>]`.
The blocker was the "all columns" case with the generic signature an empty
slice can't infer its type:
```rust
df.fill_nan(val, &[])?; // doesn't compile: can't infer T
df.fill_nan(val, &[] as &[Column])?; // works but ugly
```
Making callers annotate &[] for the common case didn't seem worth it just to
accept Into<Column>. &[&str] it is both cases stay clean:
```rust
df.fill_nan(val, &["a", "c"])?;
df.fill_nan(val, &[])?;
```
wdyt?
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