polars_core/chunked_array/ops/
shift.rs

1use num_traits::{abs, clamp};
2
3use crate::prelude::*;
4use crate::series::implementations::null::NullChunked;
5
6impl<'a, T> ChunkShiftFill<T, Option<T::Physical<'a>>> for ChunkedArray<T>
7where
8    T: PolarsDataType<IsNested = FalseT, IsObject = FalseT>,
9    ChunkedArray<T>: ChunkFull<T::Physical<'a>> + ChunkFullNull,
10    for<'b> T::Physical<'b>: TotalOrd,
11{
12    fn shift_and_fill(&self, periods: i64, fill_value: Option<T::Physical<'a>>) -> ChunkedArray<T>
13where {
14        let fill_length = abs(periods) as usize;
15        if fill_length >= self.len() {
16            return match fill_value {
17                Some(fill) => ChunkedArray::full(self.name().clone(), fill, self.len()),
18                None => ChunkedArray::full_null(self.name().clone(), self.len()),
19            };
20        }
21        let slice_offset = (-periods).max(0);
22        let length = self.len() - fill_length;
23        let mut slice = self.slice(slice_offset, length);
24
25        let mut fill = match fill_value {
26            Some(val) => ChunkedArray::full(self.name().clone(), val, fill_length),
27            None => ChunkedArray::full_null(self.name().clone(), fill_length),
28        };
29
30        if periods < 0 {
31            slice.append(&fill).unwrap();
32            slice
33        } else {
34            fill.append(&slice).unwrap();
35            fill
36        }
37    }
38}
39
40impl<'a, T> ChunkShift<T> for ChunkedArray<T>
41where
42    T: PolarsDataType<IsNested = FalseT, IsObject = FalseT>,
43    ChunkedArray<T>: ChunkFull<T::Physical<'a>> + ChunkFullNull,
44    for<'b> T::Physical<'b>: TotalOrd,
45{
46    fn shift(&self, periods: i64) -> ChunkedArray<T> {
47        self.shift_and_fill(periods, None)
48    }
49}
50
51impl ChunkShiftFill<ListType, Option<&Series>> for ListChunked {
52    fn shift_and_fill(&self, periods: i64, fill_value: Option<&Series>) -> ListChunked {
53        // This has its own implementation because a ListChunked cannot have a full-null without
54        // knowing the inner type
55        let periods = clamp(periods, -(self.len() as i64), self.len() as i64);
56        let slice_offset = (-periods).max(0);
57        let length = self.len() - abs(periods) as usize;
58        let mut slice = self.slice(slice_offset, length);
59
60        let fill_length = abs(periods) as usize;
61        let mut fill = match fill_value {
62            Some(val) => Self::full(self.name().clone(), val, fill_length),
63            None => ListChunked::full_null_with_dtype(
64                self.name().clone(),
65                fill_length,
66                self.inner_dtype(),
67            ),
68        };
69
70        if periods < 0 {
71            slice.append(&fill).unwrap();
72            slice
73        } else {
74            fill.append(&slice).unwrap();
75            fill
76        }
77    }
78}
79
80impl ChunkShift<ListType> for ListChunked {
81    fn shift(&self, periods: i64) -> Self {
82        self.shift_and_fill(periods, None)
83    }
84}
85
86#[cfg(feature = "dtype-array")]
87impl ChunkShiftFill<FixedSizeListType, Option<&Series>> for ArrayChunked {
88    fn shift_and_fill(&self, periods: i64, fill_value: Option<&Series>) -> ArrayChunked {
89        // This has its own implementation because a ArrayChunked cannot have a full-null without
90        // knowing the inner type
91        let periods = clamp(periods, -(self.len() as i64), self.len() as i64);
92        let slice_offset = (-periods).max(0);
93        let length = self.len() - abs(periods) as usize;
94        let mut slice = self.slice(slice_offset, length);
95
96        let fill_length = abs(periods) as usize;
97        let mut fill = match fill_value {
98            Some(val) => Self::full(self.name().clone(), val, fill_length),
99            None => ArrayChunked::full_null_with_dtype(
100                self.name().clone(),
101                fill_length,
102                self.inner_dtype(),
103                0,
104            ),
105        };
106
107        if periods < 0 {
108            slice.append(&fill).unwrap();
109            slice
110        } else {
111            fill.append(&slice).unwrap();
112            fill
113        }
114    }
115}
116
117#[cfg(feature = "dtype-array")]
118impl ChunkShift<FixedSizeListType> for ArrayChunked {
119    fn shift(&self, periods: i64) -> Self {
120        self.shift_and_fill(periods, None)
121    }
122}
123
124#[cfg(feature = "object")]
125impl<T: PolarsObject> ChunkShiftFill<ObjectType<T>, Option<ObjectType<T>>> for ObjectChunked<T> {
126    fn shift_and_fill(
127        &self,
128        _periods: i64,
129        _fill_value: Option<ObjectType<T>>,
130    ) -> ChunkedArray<ObjectType<T>> {
131        todo!()
132    }
133}
134#[cfg(feature = "object")]
135impl<T: PolarsObject> ChunkShift<ObjectType<T>> for ObjectChunked<T> {
136    fn shift(&self, periods: i64) -> Self {
137        self.shift_and_fill(periods, None)
138    }
139}
140
141#[cfg(feature = "dtype-struct")]
142impl ChunkShift<StructType> for StructChunked {
143    fn shift(&self, periods: i64) -> ChunkedArray<StructType> {
144        // This has its own implementation because a ArrayChunked cannot have a full-null without
145        // knowing the inner type
146        let periods = clamp(periods, -(self.len() as i64), self.len() as i64);
147        let slice_offset = (-periods).max(0);
148        let length = self.len() - abs(periods) as usize;
149        let mut slice = self.slice(slice_offset, length);
150
151        let fill_length = abs(periods) as usize;
152
153        // Go via null, so the cast creates the proper struct type.
154        let fill = NullChunked::new(self.name().clone(), fill_length)
155            .cast(self.dtype(), Default::default())
156            .unwrap();
157        let mut fill = fill.struct_().unwrap().clone();
158
159        if periods < 0 {
160            slice.append(&fill).unwrap();
161            slice
162        } else {
163            fill.append(&slice).unwrap();
164            fill
165        }
166    }
167}
168
169#[cfg(test)]
170mod test {
171    use crate::prelude::*;
172
173    #[test]
174    fn test_shift() {
175        let ca = Int32Chunked::new(PlSmallStr::EMPTY, &[1, 2, 3]);
176
177        // shift by 0, 1, 2, 3, 4
178        let shifted = ca.shift_and_fill(0, Some(5));
179        assert_eq!(Vec::from(&shifted), &[Some(1), Some(2), Some(3)]);
180        let shifted = ca.shift_and_fill(1, Some(5));
181        assert_eq!(Vec::from(&shifted), &[Some(5), Some(1), Some(2)]);
182        let shifted = ca.shift_and_fill(2, Some(5));
183        assert_eq!(Vec::from(&shifted), &[Some(5), Some(5), Some(1)]);
184        let shifted = ca.shift_and_fill(3, Some(5));
185        assert_eq!(Vec::from(&shifted), &[Some(5), Some(5), Some(5)]);
186        let shifted = ca.shift_and_fill(4, Some(5));
187        assert_eq!(Vec::from(&shifted), &[Some(5), Some(5), Some(5)]);
188
189        // shift by -1, -2, -3, -4
190        let shifted = ca.shift_and_fill(-1, Some(5));
191        assert_eq!(Vec::from(&shifted), &[Some(2), Some(3), Some(5)]);
192        let shifted = ca.shift_and_fill(-2, Some(5));
193        assert_eq!(Vec::from(&shifted), &[Some(3), Some(5), Some(5)]);
194        let shifted = ca.shift_and_fill(-3, Some(5));
195        assert_eq!(Vec::from(&shifted), &[Some(5), Some(5), Some(5)]);
196        let shifted = ca.shift_and_fill(-4, Some(5));
197        assert_eq!(Vec::from(&shifted), &[Some(5), Some(5), Some(5)]);
198
199        // fill with None
200        let shifted = ca.shift_and_fill(1, None);
201        assert_eq!(Vec::from(&shifted), &[None, Some(1), Some(2)]);
202        let shifted = ca.shift_and_fill(10, None);
203        assert_eq!(Vec::from(&shifted), &[None, None, None]);
204        let shifted = ca.shift_and_fill(-2, None);
205        assert_eq!(Vec::from(&shifted), &[Some(3), None, None]);
206
207        // string
208        let s = Series::new(PlSmallStr::from_static("a"), ["a", "b", "c"]);
209        let shifted = s.shift(-1);
210        assert_eq!(
211            Vec::from(shifted.str().unwrap()),
212            &[Some("b"), Some("c"), None]
213        );
214    }
215}
polars_core/chunked_array/ops/shift.rs

polars_core/chunked_array/ops/
shift.rs
