Method select

datafusion/core/src/dataframe/mod.rs:411–437

Project arbitrary expressions (like SQL SELECT expressions) into a new `DataFrame`. The output `DataFrame` has one column for each element in `expr_list`. # Example ``` # use datafusion::prelude::*; # use datafusion::error::Result; # use datafusion_common::assert_batches_sorted_eq; # #[tokio::main] # async fn main() -> Result<()> { let ctx = SessionContext::new(); let df = ctx .read_csv("tests/d

(
        self,
        expr_list: impl IntoIterator<Item = impl Into<SelectExpr>>,
    )

    /// # }
    /// ```
    pub fn select(
        self,
        expr_list: impl IntoIterator<Item = impl Into<SelectExpr>>,
    ) -> Result<DataFrame> {
        let expr_list: Vec<SelectExpr> =
            expr_list.into_iter().map(|e| e.into()).collect::<Vec<_>>();

        let expressions = expr_list.iter().filter_map(|e| match e {
            SelectExpr::Expression(expr) => Some(expr),
            _ => None,
        });

        let window_func_exprs = find_window_exprs(expressions);
        let plan = if window_func_exprs.is_empty() {
            self.plan
        } else {
            LogicalPlanBuilder::window_plan(self.plan, window_func_exprs)?
        };

        let project_plan = LogicalPlanBuilder::from(plan).project(expr_list)?.build()?;

        Ok(DataFrame {
            session_state: self.session_state,
            plan: project_plan,
            projection_requires_validation: false,
        })
    }

    /// Returns a new DataFrame containing all columns except the specified columns.
    ///