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| 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 | + |
| 18 | +//! [`ScalarUDFImpl`] definitions for cosine_distance function. |
| 19 | +
|
| 20 | +use crate::utils::make_scalar_function; |
| 21 | +use arrow::array::{Array, ArrayRef, Float64Array, OffsetSizeTrait}; |
| 22 | +use arrow::datatypes::{ |
| 23 | + DataType, |
| 24 | + DataType::{FixedSizeList, LargeList, List, Null}, |
| 25 | + Field, |
| 26 | +}; |
| 27 | +use datafusion_common::cast::{as_float64_array, as_generic_list_array}; |
| 28 | +use datafusion_common::utils::{ListCoercion, coerced_type_with_base_type_only}; |
| 29 | +use datafusion_common::{ |
| 30 | + Result, exec_err, internal_err, plan_err, utils::take_function_args, |
| 31 | +}; |
| 32 | +use datafusion_expr::{ |
| 33 | + ColumnarValue, Documentation, ScalarFunctionArgs, ScalarUDFImpl, Signature, |
| 34 | + Volatility, |
| 35 | +}; |
| 36 | +use datafusion_macros::user_doc; |
| 37 | +use std::sync::Arc; |
| 38 | + |
| 39 | +make_udf_expr_and_func!( |
| 40 | + CosineDistance, |
| 41 | + cosine_distance, |
| 42 | + array1 array2, |
| 43 | + "returns the cosine distance between two numeric arrays.", |
| 44 | + cosine_distance_udf |
| 45 | +); |
| 46 | + |
| 47 | +#[user_doc( |
| 48 | + doc_section(label = "Array Functions"), |
| 49 | + description = "Returns the cosine distance between two input arrays of equal length. The cosine distance is defined as 1 - cosine_similarity, i.e. `1 - dot(a,b) / (||a|| * ||b||)`. Returns NULL if either array is NULL or contains only zeros.", |
| 50 | + syntax_example = "cosine_distance(array1, array2)", |
| 51 | + sql_example = r#"```sql |
| 52 | +> select cosine_distance([1.0, 0.0], [0.0, 1.0]); |
| 53 | ++-----------------------------------------------+ |
| 54 | +| cosine_distance(List([1.0,0.0]),List([0.0,1.0])) | |
| 55 | ++-----------------------------------------------+ |
| 56 | +| 1.0 | |
| 57 | ++-----------------------------------------------+ |
| 58 | +```"#, |
| 59 | + argument( |
| 60 | + name = "array1", |
| 61 | + description = "Array expression. Can be a constant, column, or function, and any combination of array operators." |
| 62 | + ), |
| 63 | + argument( |
| 64 | + name = "array2", |
| 65 | + description = "Array expression. Can be a constant, column, or function, and any combination of array operators." |
| 66 | + ) |
| 67 | +)] |
| 68 | +#[derive(Debug, PartialEq, Eq, Hash)] |
| 69 | +pub struct CosineDistance { |
| 70 | + signature: Signature, |
| 71 | +} |
| 72 | + |
| 73 | +impl Default for CosineDistance { |
| 74 | + fn default() -> Self { |
| 75 | + Self::new() |
| 76 | + } |
| 77 | +} |
| 78 | + |
| 79 | +impl CosineDistance { |
| 80 | + pub fn new() -> Self { |
| 81 | + Self { |
| 82 | + signature: Signature::user_defined(Volatility::Immutable), |
| 83 | + } |
| 84 | + } |
| 85 | +} |
| 86 | + |
| 87 | +impl ScalarUDFImpl for CosineDistance { |
| 88 | + fn name(&self) -> &str { |
| 89 | + "cosine_distance" |
| 90 | + } |
| 91 | + |
| 92 | + fn signature(&self) -> &Signature { |
| 93 | + &self.signature |
| 94 | + } |
| 95 | + |
| 96 | + fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType> { |
| 97 | + Ok(DataType::Float64) |
| 98 | + } |
| 99 | + |
| 100 | + fn coerce_types(&self, arg_types: &[DataType]) -> Result<Vec<DataType>> { |
| 101 | + let [_, _] = take_function_args(self.name(), arg_types)?; |
| 102 | + let coercion = Some(&ListCoercion::FixedSizedListToList); |
| 103 | + |
| 104 | + for arg_type in arg_types { |
| 105 | + if !matches!(arg_type, Null | List(_) | LargeList(_) | FixedSizeList(..)) { |
| 106 | + return plan_err!("{} does not support type {arg_type}", self.name()); |
| 107 | + } |
| 108 | + } |
| 109 | + |
| 110 | + // If any input is `LargeList`, both sides must be widened to `LargeList` |
| 111 | + // so the runtime dispatch in `cosine_distance_inner` sees a homogeneous |
| 112 | + // pair. Follows the pattern in `ArrayConcat::coerce_types`. |
| 113 | + let any_large_list = arg_types.iter().any(|t| matches!(t, LargeList(_))); |
| 114 | + |
| 115 | + let coerced = arg_types |
| 116 | + .iter() |
| 117 | + .map(|arg_type| { |
| 118 | + if matches!(arg_type, Null) { |
| 119 | + let field = Arc::new(Field::new_list_field(DataType::Float64, true)); |
| 120 | + return if any_large_list { |
| 121 | + LargeList(field) |
| 122 | + } else { |
| 123 | + List(field) |
| 124 | + }; |
| 125 | + } |
| 126 | + let coerced = coerced_type_with_base_type_only( |
| 127 | + arg_type, |
| 128 | + &DataType::Float64, |
| 129 | + coercion, |
| 130 | + ); |
| 131 | + match coerced { |
| 132 | + List(field) if any_large_list => LargeList(field), |
| 133 | + other => other, |
| 134 | + } |
| 135 | + }) |
| 136 | + .collect(); |
| 137 | + |
| 138 | + Ok(coerced) |
| 139 | + } |
| 140 | + |
| 141 | + fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> { |
| 142 | + make_scalar_function(cosine_distance_inner)(&args.args) |
| 143 | + } |
| 144 | + |
| 145 | + fn documentation(&self) -> Option<&Documentation> { |
| 146 | + self.doc() |
| 147 | + } |
| 148 | +} |
| 149 | + |
| 150 | +fn cosine_distance_inner(args: &[ArrayRef]) -> Result<ArrayRef> { |
| 151 | + let [array1, array2] = take_function_args("cosine_distance", args)?; |
| 152 | + match (array1.data_type(), array2.data_type()) { |
| 153 | + (List(_), List(_)) => general_cosine_distance::<i32>(args), |
| 154 | + (LargeList(_), LargeList(_)) => general_cosine_distance::<i64>(args), |
| 155 | + (arg_type1, arg_type2) => internal_err!( |
| 156 | + "cosine_distance received unexpected types after coercion: {arg_type1} and {arg_type2}" |
| 157 | + ), |
| 158 | + } |
| 159 | +} |
| 160 | + |
| 161 | +fn general_cosine_distance<O: OffsetSizeTrait>(arrays: &[ArrayRef]) -> Result<ArrayRef> { |
| 162 | + let list_array1 = as_generic_list_array::<O>(&arrays[0])?; |
| 163 | + let list_array2 = as_generic_list_array::<O>(&arrays[1])?; |
| 164 | + |
| 165 | + let values1 = as_float64_array(list_array1.values())?; |
| 166 | + let values2 = as_float64_array(list_array2.values())?; |
| 167 | + let offsets1 = list_array1.value_offsets(); |
| 168 | + let offsets2 = list_array2.value_offsets(); |
| 169 | + |
| 170 | + let mut builder = Float64Array::builder(list_array1.len()); |
| 171 | + for row in 0..list_array1.len() { |
| 172 | + if list_array1.is_null(row) || list_array2.is_null(row) { |
| 173 | + builder.append_null(); |
| 174 | + continue; |
| 175 | + } |
| 176 | + |
| 177 | + let start1 = offsets1[row].as_usize(); |
| 178 | + let end1 = offsets1[row + 1].as_usize(); |
| 179 | + let start2 = offsets2[row].as_usize(); |
| 180 | + let end2 = offsets2[row + 1].as_usize(); |
| 181 | + let len1 = end1 - start1; |
| 182 | + let len2 = end2 - start2; |
| 183 | + |
| 184 | + if len1 != len2 { |
| 185 | + return exec_err!( |
| 186 | + "cosine_distance requires both list inputs to have the same length, got {len1} and {len2}" |
| 187 | + ); |
| 188 | + } |
| 189 | + |
| 190 | + let slice1 = values1.slice(start1, len1); |
| 191 | + let slice2 = values2.slice(start2, len2); |
| 192 | + if slice1.null_count() != 0 || slice2.null_count() != 0 { |
| 193 | + builder.append_null(); |
| 194 | + continue; |
| 195 | + } |
| 196 | + |
| 197 | + let vals1 = slice1.values(); |
| 198 | + let vals2 = slice2.values(); |
| 199 | + |
| 200 | + let mut dot = 0.0; |
| 201 | + let mut sq1 = 0.0; |
| 202 | + let mut sq2 = 0.0; |
| 203 | + for i in 0..len1 { |
| 204 | + let a = vals1[i]; |
| 205 | + let b = vals2[i]; |
| 206 | + dot += a * b; |
| 207 | + sq1 += a * a; |
| 208 | + sq2 += b * b; |
| 209 | + } |
| 210 | + |
| 211 | + if sq1 == 0.0 || sq2 == 0.0 { |
| 212 | + builder.append_null(); |
| 213 | + } else { |
| 214 | + builder.append_value(1.0 - dot / (sq1.sqrt() * sq2.sqrt())); |
| 215 | + } |
| 216 | + } |
| 217 | + |
| 218 | + Ok(Arc::new(builder.finish()) as ArrayRef) |
| 219 | +} |
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