From 813c0aef8c1369a8cdaa8795b004b9640d67126d Mon Sep 17 00:00:00 2001
From: Andrew Gazelka <andrew.gazelka@gmail.com>
Date: Tue, 19 Nov 2024 23:15:27 -0800
Subject: [PATCH] [FEAT] connect: add `df.filter`

---
 .../src/translation/logical_plan.rs           |  6 ++++-
 .../src/translation/logical_plan/filter.rs    | 25 +++++++++++++++++++
 tests/connect/test_filter.py                  | 19 ++++++++++++++
 3 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 src/daft-connect/src/translation/logical_plan/filter.rs
 create mode 100644 tests/connect/test_filter.py

diff --git a/src/daft-connect/src/translation/logical_plan.rs b/src/daft-connect/src/translation/logical_plan.rs
index 947e0cd0d3..1d4d1809f0 100644
--- a/src/daft-connect/src/translation/logical_plan.rs
+++ b/src/daft-connect/src/translation/logical_plan.rs
@@ -3,9 +3,12 @@ use eyre::{bail, Context};
 use spark_connect::{relation::RelType, Relation};
 use tracing::warn;
 
-use crate::translation::logical_plan::{aggregate::aggregate, project::project, range::range};
+use crate::translation::logical_plan::{
+    aggregate::aggregate, filter::filter, project::project, range::range,
+};
 
 mod aggregate;
+mod filter;
 mod project;
 mod range;
 
@@ -21,6 +24,7 @@ pub fn to_logical_plan(relation: Relation) -> eyre::Result<LogicalPlanBuilder> {
     match rel_type {
         RelType::Range(r) => range(r).wrap_err("Failed to apply range to logical plan"),
         RelType::Project(p) => project(*p).wrap_err("Failed to apply project to logical plan"),
+        RelType::Filter(f) => filter(*f).wrap_err("Failed to apply filter to logical plan"),
         RelType::Aggregate(a) => {
             aggregate(*a).wrap_err("Failed to apply aggregate to logical plan")
         }
diff --git a/src/daft-connect/src/translation/logical_plan/filter.rs b/src/daft-connect/src/translation/logical_plan/filter.rs
new file mode 100644
index 0000000000..2a5df304f2
--- /dev/null
+++ b/src/daft-connect/src/translation/logical_plan/filter.rs
@@ -0,0 +1,25 @@
+use eyre::bail;
+
+use crate::translation::{to_daft_expr, to_logical_plan};
+
+pub fn filter(
+    filter: spark_connect::Filter,
+) -> eyre::Result<daft_logical_plan::LogicalPlanBuilder> {
+    let spark_connect::Filter { input, condition } = filter;
+
+    let Some(input) = input else {
+        bail!("input is required");
+    };
+
+    let Some(condition) = condition else {
+        bail!("condition is required");
+    };
+
+    let condition = to_daft_expr(&condition)?;
+
+    let plan = to_logical_plan(*input)?;
+
+    let plan = plan.filter(condition)?;
+
+    Ok(plan)
+}
diff --git a/tests/connect/test_filter.py b/tests/connect/test_filter.py
new file mode 100644
index 0000000000..1586c7e7b5
--- /dev/null
+++ b/tests/connect/test_filter.py
@@ -0,0 +1,19 @@
+from __future__ import annotations
+
+from pyspark.sql.functions import col
+
+
+def test_filter(spark_session):
+    # Create DataFrame from range(10)
+    df = spark_session.range(10)
+
+    # Filter for values less than 5
+    df_filtered = df.filter(col("id") < 5)
+
+    # Verify the schema is unchanged after filter
+    assert df_filtered.schema == df.schema, "Schema should be unchanged after filter"
+
+    # Verify the filtered data is correct
+    df_filtered_pandas = df_filtered.toPandas()
+    assert len(df_filtered_pandas) == 5, "Should have 5 rows after filtering < 5"
+    assert all(df_filtered_pandas["id"] < 5), "All values should be less than 5"