Method from_indices

datafusion/physical-expr/src/projection.rs:229–239

Creates a [`ProjectionExpr`] from a list of column indices. This is a convenience method for creating simple column-only projections, where each projection expression is a reference to a column in the input schema. # Behavior - Ordering: the output projection preserves the exact order of indices provided in the input slice For example, `[2, 0, 1]` will produce projections for columns 2, 0, then

(indices: &[usize], schema: &Schema)

    /// assert_eq!(projection_with_dups.as_ref()[2].alias, "b");
    /// ```
    pub fn from_indices(indices: &[usize], schema: &Schema) -> Self {
        let projection_exprs = indices.iter().map(|&i| {
            let field = schema.field(i);
            ProjectionExpr {
                expr: Arc::new(Column::new(field.name(), i)),
                alias: field.name().clone(),
            }
        });

        Self::from_iter(projection_exprs)
    }

    /// Returns an iterator over the projection expressions
    pub fn iter(&self) -> impl Iterator<Item = &ProjectionExpr> {