datafusion_python/expr/
projection.rs

1// Licensed to the Apache Software Foundation (ASF) under one
2// or more contributor license agreements.  See the NOTICE file
3// distributed with this work for additional information
4// regarding copyright ownership.  The ASF licenses this file
5// to you under the Apache License, Version 2.0 (the
6// "License"); you may not use this file except in compliance
7// with the License.  You may obtain a copy of the License at
8//
9//   http://www.apache.org/licenses/LICENSE-2.0
10//
11// Unless required by applicable law or agreed to in writing,
12// software distributed under the License is distributed on an
13// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
14// KIND, either express or implied.  See the License for the
15// specific language governing permissions and limitations
16// under the License.
17
18use datafusion::logical_expr::logical_plan::Projection;
19use datafusion::logical_expr::Expr;
20use pyo3::{prelude::*, IntoPyObjectExt};
21use std::fmt::{self, Display, Formatter};
22
23use crate::common::df_schema::PyDFSchema;
24use crate::expr::logical_node::LogicalNode;
25use crate::expr::PyExpr;
26use crate::sql::logical::PyLogicalPlan;
27
28#[pyclass(name = "Projection", module = "datafusion.expr", subclass)]
29#[derive(Clone)]
30pub struct PyProjection {
31    pub projection: Projection,
32}
33
34impl PyProjection {
35    pub fn new(projection: Projection) -> Self {
36        Self { projection }
37    }
38}
39
40impl From<Projection> for PyProjection {
41    fn from(projection: Projection) -> PyProjection {
42        PyProjection { projection }
43    }
44}
45
46impl From<PyProjection> for Projection {
47    fn from(proj: PyProjection) -> Self {
48        proj.projection
49    }
50}
51
52impl Display for PyProjection {
53    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
54        write!(
55            f,
56            "Projection
57            \nExpr(s): {:?}
58            \nInput: {:?}
59            \nProjected Schema: {:?}",
60            &self.projection.expr, &self.projection.input, &self.projection.schema,
61        )
62    }
63}
64
65#[pymethods]
66impl PyProjection {
67    /// Retrieves the expressions for this `Projection`
68    fn projections(&self) -> PyResult<Vec<PyExpr>> {
69        Ok(self
70            .projection
71            .expr
72            .iter()
73            .map(|e| PyExpr::from(e.clone()))
74            .collect())
75    }
76
77    /// Retrieves the input `LogicalPlan` to this `Projection` node
78    fn input(&self) -> PyResult<Vec<PyLogicalPlan>> {
79        Ok(Self::inputs(self))
80    }
81
82    /// Resulting Schema for this `Projection` node instance
83    fn schema(&self) -> PyResult<PyDFSchema> {
84        Ok((*self.projection.schema).clone().into())
85    }
86
87    fn __repr__(&self) -> PyResult<String> {
88        Ok(format!("Projection({})", self))
89    }
90
91    fn __name__(&self) -> PyResult<String> {
92        Ok("Projection".to_string())
93    }
94}
95
96impl PyProjection {
97    /// Projection: Gets the names of the fields that should be projected
98    pub fn projected_expressions(local_expr: &PyExpr) -> Vec<PyExpr> {
99        let mut projs: Vec<PyExpr> = Vec::new();
100        match &local_expr.expr {
101            Expr::Alias(alias) => {
102                let py_expr: PyExpr = PyExpr::from(*alias.expr.clone());
103                projs.extend_from_slice(Self::projected_expressions(&py_expr).as_slice());
104            }
105            _ => projs.push(local_expr.clone()),
106        }
107        projs
108    }
109}
110
111impl LogicalNode for PyProjection {
112    fn inputs(&self) -> Vec<PyLogicalPlan> {
113        vec![PyLogicalPlan::from((*self.projection.input).clone())]
114    }
115
116    fn to_variant<'py>(&self, py: Python<'py>) -> PyResult<Bound<'py, PyAny>> {
117        self.clone().into_bound_py_any(py)
118    }
119}
datafusion_python/expr/projection.rs

datafusion_python/expr/
projection.rs
