Document and allow more operations on decimals

lib/explorer/series.ex

@@ -3262,6 +3262,7 @@ defmodule Explorer.Series do
     * `:time`
     * `:datetime`
     * `:duration`
+    * `:decimal`
 
   ## Examples
 
@@ -3344,6 +3345,7 @@ defmodule Explorer.Series do
 
     * floats: #{Shared.inspect_dtypes(@float_dtypes, backsticks: true)}
     * integers: #{Shared.inspect_dtypes(@integer_types, backsticks: true)}
+    * `:decimal`
 
   ## Examples
 
@@ -3422,6 +3424,7 @@ defmodule Explorer.Series do
 
     * floats: #{Shared.inspect_dtypes(@float_dtypes, backsticks: true)}
     * integers: #{Shared.inspect_dtypes(@integer_types, backsticks: true)}
+    * `:decimal`
 
   ## Examples
 
@@ -3492,7 +3495,7 @@ defmodule Explorer.Series do
 
     * floats: #{Shared.inspect_dtypes(@float_dtypes, backsticks: true)}
     * integers: #{Shared.inspect_dtypes(@integer_types, backsticks: true)}
-    * decimals - returning decimal series.
+    * `:decimal` - returning decimal series.
 
   ## Examples
 
@@ -3549,7 +3552,7 @@ defmodule Explorer.Series do
 
     * floats: #{Shared.inspect_dtypes(@float_dtypes, backsticks: true)}
     * integers: #{Shared.inspect_dtypes(@integer_types, backsticks: true)}
-    * decimals - returning f64 series.
+    * `:decimal` - returning f64 series.
 
   ## Examples
 
@@ -3629,7 +3632,7 @@ defmodule Explorer.Series do
 
     * floats: #{Shared.inspect_dtypes(@float_dtypes, backsticks: true)}
     * integers: #{Shared.inspect_dtypes(@integer_types, backsticks: true)}
-    * decimals - returning f64 series.
+    * `:decimal` - returning f64 series.
 
   ## Examples
 
@@ -3701,7 +3704,7 @@ defmodule Explorer.Series do
 
     * floats: #{Shared.inspect_dtypes(@float_dtypes, backsticks: true)}
     * integers: #{Shared.inspect_dtypes(@integer_types, backsticks: true)}
-    * decimals.
+    * `:decimal` - returns f64 series.
 
   ## Examples
 
@@ -3726,7 +3729,7 @@ defmodule Explorer.Series do
 
     * floats: #{Shared.inspect_dtypes(@float_dtypes, backsticks: true)}
     * integers: #{Shared.inspect_dtypes(@integer_types, backsticks: true)}
-    * decimals.
+    * `:decimal`.
 
   ## Examples
 

lib/explorer/shared.ex

@@ -378,6 +378,7 @@ defmodule Explorer.Shared do
   def merge_numeric_dtype({:decimal, _, _} = decimal, :null), do: decimal
   def merge_numeric_dtype(:null, {:decimal, _, _} = decimal), do: decimal
 
+  # For now, float has priority over decimals due to Polars.
   def merge_numeric_dtype({:decimal, _, _}, {:f, _} = float), do: float
   def merge_numeric_dtype({:f, _} = float, {:decimal, _, _}), do: float
 
@@ -512,7 +513,7 @@ defmodule Explorer.Shared do
   def dtype_to_string({:f, size}), do: "f" <> Integer.to_string(size)
   def dtype_to_string({:s, size}), do: "s" <> Integer.to_string(size)
   def dtype_to_string({:u, size}), do: "u" <> Integer.to_string(size)
-  def dtype_to_string({:decimal, precision, scale}), do: "decimal[#{precision}, #{scale}]"
+  def dtype_to_string({:decimal, precision, scale}), do: "decimal[#{precision || "*"}, #{scale}]"
   def dtype_to_string(other) when is_atom(other), do: Atom.to_string(other)
 
   defp precision_string(:millisecond), do: "ms"

native/explorer/src/datatypes.rs

@@ -574,6 +574,16 @@ pub struct ExDecimal {
 }
 
 impl ExDecimal {
+    pub fn new(signed_coef: i128, scale: usize) -> Self {
+        Self {
+            coef: signed_coef
+                .abs()
+                .try_into()
+                .expect("signed coef is too large for u64"),
+            sign: if signed_coef >= 0 { 1 } else { -1 },
+            exp: -(scale as i64),
+        }
+    }
     pub fn signed_coef(self) -> i128 {
         self.sign as i128 * self.coef as i128
     }

native/explorer/src/series.rs

@@ -774,7 +774,9 @@ pub fn s_min(env: Env, s: ExSeries) -> Result<Term, ExplorerError> {
         DataType::UInt16 => Ok(s.min::<u16>()?.encode(env)),
         DataType::UInt32 => Ok(s.min::<u32>()?.encode(env)),
         DataType::UInt64 => Ok(s.min::<u64>()?.encode(env)),
-        DataType::Float32 | DataType::Float64 => Ok(term_from_optional_float(s.min::<f64>()?, env)),
+        DataType::Float32 | DataType::Float64 | DataType::Decimal(_, _) => {
+            Ok(term_from_optional_float(s.min::<f64>()?, env))
+        }
         DataType::Date => Ok(s.min::<i32>()?.map(ExDate::from).encode(env)),
         DataType::Time => Ok(s.min::<i64>()?.map(ExTime::from).encode(env)),
         DataType::Datetime(unit, _) => Ok(s
@@ -796,7 +798,9 @@ pub fn s_max(env: Env, s: ExSeries) -> Result<Term, ExplorerError> {
         DataType::UInt16 => Ok(s.max::<u16>()?.encode(env)),
         DataType::UInt32 => Ok(s.max::<u32>()?.encode(env)),
         DataType::UInt64 => Ok(s.max::<u64>()?.encode(env)),
-        DataType::Float32 | DataType::Float64 => Ok(term_from_optional_float(s.max::<f64>()?, env)),
+        DataType::Float32 | DataType::Float64 | DataType::Decimal(_, _) => {
+            Ok(term_from_optional_float(s.max::<f64>()?, env))
+        }
         DataType::Date => Ok(s.max::<i32>()?.map(ExDate::from).encode(env)),
         DataType::Time => Ok(s.max::<i64>()?.map(ExTime::from).encode(env)),
         DataType::Datetime(unit, _) => Ok(s
@@ -817,9 +821,13 @@ pub fn s_argmin(env: Env, s: ExSeries) -> Result<Term, ExplorerError> {
     Ok(s.arg_min().encode(env))
 }
 
+fn is_numeric(dtype: &DataType) -> bool {
+    dtype.is_numeric() || matches!(dtype, DataType::Decimal(_, _))
+}
+
 #[rustler::nif(schedule = "DirtyCpu")]
 pub fn s_mean(env: Env, s: ExSeries) -> Result<Term, ExplorerError> {
-    if s.dtype().is_numeric() {
+    if is_numeric(s.dtype()) {
         Ok(term_from_optional_float(s.mean(), env))
     } else {
         panic!("mean/1 not implemented for {:?}", &s.dtype())
@@ -828,7 +836,7 @@ pub fn s_mean(env: Env, s: ExSeries) -> Result<Term, ExplorerError> {
 
 #[rustler::nif(schedule = "DirtyCpu")]
 pub fn s_median(env: Env, s: ExSeries) -> Result<Term, ExplorerError> {
-    if s.dtype().is_numeric() {
+    if is_numeric(s.dtype()) {
         Ok(term_from_optional_float(s.median(), env))
     } else {
         panic!("median/1 not implemented for {:?}", &s.dtype())
@@ -845,7 +853,7 @@ pub fn s_mode(s: ExSeries) -> Result<ExSeries, ExplorerError> {
 
 #[rustler::nif(schedule = "DirtyCpu")]
 pub fn s_product(s: ExSeries) -> Result<ExSeries, ExplorerError> {
-    if s.dtype().is_numeric() {
+    if is_numeric(s.dtype()) {
         let series = s
             .clone_inner()
             .into_frame()
@@ -863,7 +871,7 @@ pub fn s_product(s: ExSeries) -> Result<ExSeries, ExplorerError> {
 
 #[rustler::nif(schedule = "DirtyCpu")]
 pub fn s_variance(s: ExSeries, ddof: u8) -> Result<ExSeries, ExplorerError> {
-    if s.dtype().is_numeric() {
+    if is_numeric(s.dtype()) {
         let var_series = s
             .clone_inner()
             .into_frame()
@@ -881,7 +889,7 @@ pub fn s_variance(s: ExSeries, ddof: u8) -> Result<ExSeries, ExplorerError> {
 
 #[rustler::nif(schedule = "DirtyCpu")]
 pub fn s_standard_deviation(s: ExSeries, ddof: u8) -> Result<ExSeries, ExplorerError> {
-    if s.dtype().is_numeric() {
+    if is_numeric(s.dtype()) {
         let std_series = s
             .clone_inner()
             .into_frame()
@@ -899,7 +907,7 @@ pub fn s_standard_deviation(s: ExSeries, ddof: u8) -> Result<ExSeries, ExplorerE
 
 #[rustler::nif(schedule = "DirtyCpu")]
 pub fn s_skew(env: Env, s: ExSeries, bias: bool) -> Result<Term, ExplorerError> {
-    if s.dtype().is_numeric() {
+    if is_numeric(s.dtype()) {
         Ok(term_from_optional_float(s.skew(bias)?, env))
     } else {
         panic!("skew/2 not implemented for {:?}", &s.dtype())
@@ -1040,6 +1048,7 @@ pub fn s_peak_max(s: ExSeries) -> Result<ExSeries, ExplorerError> {
 
         DataType::Float32 => peak_max(s.f32()?),
         DataType::Float64 => peak_max(s.f64()?),
+        DataType::Decimal(_, _) => peak_max(s.decimal()?),
 
         DataType::Date => peak_max(s.date()?),
         DataType::Time => peak_max(s.time()?),
@@ -1066,6 +1075,7 @@ pub fn s_peak_min(s: ExSeries) -> Result<ExSeries, ExplorerError> {
 
         DataType::Float32 => peak_min(s.f32()?),
         DataType::Float64 => peak_min(s.f64()?),
+        DataType::Decimal(_, _) => peak_min(s.decimal()?),
 
         DataType::Date => peak_min(s.date()?),
         DataType::Time => peak_min(s.time()?),