feat(rust,python,cli): add SQL engine support for MOD function (#13502

)

crates/polars-sql/src/functions.rs

@@ -89,6 +89,12 @@ pub(crate) enum PolarsSQLFunctions {
     /// SELECT POW(column_1, 2) from df;
     /// ```
     Pow,
+    /// SQL 'mod' function
+    /// Returns the remainder of a numeric expression divided by another numeric expression.
+    /// ```sql
+    /// SELECT MOD(column_1, 2) from df;
+    /// ```
+    Mod,
     /// SQL 'sqrt' function
     /// Returns the square root (√) of a number.
     /// ```sql
@@ -601,6 +607,7 @@ impl PolarsSQLFunctions {
             "log10" => Self::Log10,
             "log1p" => Self::Log1p,
             "log2" => Self::Log2,
+            "mod" => Self::Mod,
             "pi" => Self::Pi,
             "pow" | "power" => Self::Pow,
             "round" => Self::Round,
@@ -742,6 +749,7 @@ impl SQLFunctionVisitor<'_> {
             Log10 => self.visit_unary(|e| e.log(10.0)),
             Log1p => self.visit_unary(Expr::log1p),
             Log2 => self.visit_unary(|e| e.log(2.0)),
+            Mod => self.visit_binary(|e1, e2| e1 % e2),
             Pow => self.visit_binary::<Expr>(Expr::pow),
             Sqrt => self.visit_unary(Expr::sqrt),
             Cbrt => self.visit_unary(Expr::cbrt),

py-polars/tests/unit/sql/test_numeric.py

@@ -7,28 +7,23 @@
 from polars.testing import assert_frame_equal, assert_series_equal
 
 
-def test_stddev_variance() -> None:
+def test_modulo() -> None:
     df = pl.DataFrame(
         {
-            "v1": [-1.0, 0.0, 1.0],
-            "v2": [5.5, 0.0, 3.0],
-            "v3": [-10, None, 10],
-            "v4": [-100, 0.0, -50.0],
+            "a": [1.5, None, 3.0, 13 / 3, 5.0],
+            "b": [6, 7, 8, 9, 10],
+            "c": [11, 12, 13, 14, 15],
+            "d": [16.5, 17.0, 18.5, None, 20.0],
         }
     )
     with pl.SQLContext(df=df) as ctx:
-        # note: we support all common aliases for std/var
         out = ctx.execute(
             """
             SELECT
-              STDEV(v1) AS "v1_std",
-              STDDEV(v2) AS "v2_std",
-              STDEV_SAMP(v3) AS "v3_std",
-              STDDEV_SAMP(v4) AS "v4_std",
-              VAR(v1) AS "v1_var",
-              VARIANCE(v2) AS "v2_var",
-              VARIANCE(v3) AS "v3_var",
-              VAR_SAMP(v4) AS "v4_var"
+              a % 2 AS a2,
+              b % 3 AS b3,
+              MOD(c, 4) AS c4,
+              MOD(d, 5.5) AS d55
             FROM df
             """
         ).collect()
@@ -37,14 +32,10 @@ def test_stddev_variance() -> None:
             out,
             pl.DataFrame(
                 {
-                    "v1_std": [1.0],
-                    "v2_std": [2.7537852736431],
-                    "v3_std": [14.142135623731],
-                    "v4_std": [50.0],
-                    "v1_var": [1.0],
-                    "v2_var": [7.5833333333333],
-                    "v3_var": [200.0],
-                    "v4_var": [2500.0],
+                    "a2": [1.5, None, 1.0, 1 / 3, 1.0],
+                    "b3": [0, 1, 2, 0, 1],
+                    "c4": [3, 0, 1, 2, 3],
+                    "d55": [0.0, 0.5, 2.0, None, 3.5],
                 }
             ),
         )
@@ -79,3 +70,46 @@ def test_round_ndigits_errors() -> None:
         InvalidOperationError, match="Invalid 'decimals' for Round: -1"
     ):
         ctx.execute("SELECT ROUND(n,-1) AS n FROM df")
+
+
+def test_stddev_variance() -> None:
+    df = pl.DataFrame(
+        {
+            "v1": [-1.0, 0.0, 1.0],
+            "v2": [5.5, 0.0, 3.0],
+            "v3": [-10, None, 10],
+            "v4": [-100, 0.0, -50.0],
+        }
+    )
+    with pl.SQLContext(df=df) as ctx:
+        # note: we support all common aliases for std/var
+        out = ctx.execute(
+            """
+            SELECT
+              STDEV(v1) AS "v1_std",
+              STDDEV(v2) AS "v2_std",
+              STDEV_SAMP(v3) AS "v3_std",
+              STDDEV_SAMP(v4) AS "v4_std",
+              VAR(v1) AS "v1_var",
+              VARIANCE(v2) AS "v2_var",
+              VARIANCE(v3) AS "v3_var",
+              VAR_SAMP(v4) AS "v4_var"
+            FROM df
+            """
+        ).collect()
+
+        assert_frame_equal(
+            out,
+            pl.DataFrame(
+                {
+                    "v1_std": [1.0],
+                    "v2_std": [2.7537852736431],
+                    "v3_std": [14.142135623731],
+                    "v4_std": [50.0],
+                    "v1_var": [1.0],
+                    "v2_var": [7.5833333333333],
+                    "v3_var": [200.0],
+                    "v4_var": [2500.0],
+                }
+            ),
+        )