1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
use num_traits::{abs, clamp};

use crate::prelude::*;

macro_rules! impl_shift_fill {
    ($self:ident, $periods:expr, $fill_value:expr) => {{
        let fill_length = abs($periods) as usize;

        if fill_length >= $self.len() {
            return match $fill_value {
                Some(fill) => Self::full($self.name(), fill, $self.len()),
                None => Self::full_null($self.name(), $self.len()),
            };
        }
        let slice_offset = (-$periods).max(0) as i64;
        let length = $self.len() - fill_length;
        let mut slice = $self.slice(slice_offset, length);

        let mut fill = match $fill_value {
            Some(val) => Self::full($self.name(), val, fill_length),
            None => Self::full_null($self.name(), fill_length),
        };

        if $periods < 0 {
            slice.append(&fill);
            slice
        } else {
            fill.append(&slice);
            fill
        }
    }};
}

impl<T> ChunkShiftFill<T, Option<T::Native>> for ChunkedArray<T>
where
    T: PolarsNumericType,
{
    fn shift_and_fill(&self, periods: i64, fill_value: Option<T::Native>) -> ChunkedArray<T> {
        impl_shift_fill!(self, periods, fill_value)
    }
}
impl<T> ChunkShift<T> for ChunkedArray<T>
where
    T: PolarsNumericType,
{
    fn shift(&self, periods: i64) -> ChunkedArray<T> {
        self.shift_and_fill(periods, None)
    }
}

impl ChunkShiftFill<BooleanType, Option<bool>> for BooleanChunked {
    fn shift_and_fill(&self, periods: i64, fill_value: Option<bool>) -> BooleanChunked {
        impl_shift_fill!(self, periods, fill_value)
    }
}

impl ChunkShift<BooleanType> for BooleanChunked {
    fn shift(&self, periods: i64) -> Self {
        self.shift_and_fill(periods, None)
    }
}

impl ChunkShiftFill<StringType, Option<&str>> for StringChunked {
    fn shift_and_fill(&self, periods: i64, fill_value: Option<&str>) -> StringChunked {
        let ca = self.as_binary();
        unsafe {
            ca.shift_and_fill(periods, fill_value.map(|v| v.as_bytes()))
                .to_string_unchecked()
        }
    }
}

impl ChunkShiftFill<BinaryType, Option<&[u8]>> for BinaryChunked {
    fn shift_and_fill(&self, periods: i64, fill_value: Option<&[u8]>) -> BinaryChunked {
        impl_shift_fill!(self, periods, fill_value)
    }
}

impl ChunkShiftFill<BinaryOffsetType, Option<&[u8]>> for BinaryOffsetChunked {
    fn shift_and_fill(&self, periods: i64, fill_value: Option<&[u8]>) -> BinaryOffsetChunked {
        impl_shift_fill!(self, periods, fill_value)
    }
}

impl ChunkShift<StringType> for StringChunked {
    fn shift(&self, periods: i64) -> Self {
        self.shift_and_fill(periods, None)
    }
}

impl ChunkShift<BinaryType> for BinaryChunked {
    fn shift(&self, periods: i64) -> Self {
        self.shift_and_fill(periods, None)
    }
}

impl ChunkShift<BinaryOffsetType> for BinaryOffsetChunked {
    fn shift(&self, periods: i64) -> Self {
        self.shift_and_fill(periods, None)
    }
}

impl ChunkShiftFill<ListType, Option<&Series>> for ListChunked {
    fn shift_and_fill(&self, periods: i64, fill_value: Option<&Series>) -> ListChunked {
        // This has its own implementation because a ListChunked cannot have a full-null without
        // knowing the inner type
        let periods = clamp(periods, -(self.len() as i64), self.len() as i64);
        let slice_offset = (-periods).max(0);
        let length = self.len() - abs(periods) as usize;
        let mut slice = self.slice(slice_offset, length);

        let fill_length = abs(periods) as usize;
        let mut fill = match fill_value {
            Some(val) => Self::full(self.name(), val, fill_length),
            None => ListChunked::full_null_with_dtype(self.name(), fill_length, self.inner_dtype()),
        };

        if periods < 0 {
            slice.append(&fill).unwrap();
            slice
        } else {
            fill.append(&slice).unwrap();
            fill
        }
    }
}

impl ChunkShift<ListType> for ListChunked {
    fn shift(&self, periods: i64) -> Self {
        self.shift_and_fill(periods, None)
    }
}

#[cfg(feature = "dtype-array")]
impl ChunkShiftFill<FixedSizeListType, Option<&Series>> for ArrayChunked {
    fn shift_and_fill(&self, periods: i64, fill_value: Option<&Series>) -> ArrayChunked {
        // This has its own implementation because a ArrayChunked cannot have a full-null without
        // knowing the inner type
        let periods = clamp(periods, -(self.len() as i64), self.len() as i64);
        let slice_offset = (-periods).max(0);
        let length = self.len() - abs(periods) as usize;
        let mut slice = self.slice(slice_offset, length);

        let fill_length = abs(periods) as usize;
        let mut fill = match fill_value {
            Some(val) => Self::full(self.name(), val, fill_length),
            None => {
                ArrayChunked::full_null_with_dtype(self.name(), fill_length, self.inner_dtype(), 0)
            },
        };

        if periods < 0 {
            slice.append(&fill).unwrap();
            slice
        } else {
            fill.append(&slice).unwrap();
            fill
        }
    }
}

#[cfg(feature = "dtype-array")]
impl ChunkShift<FixedSizeListType> for ArrayChunked {
    fn shift(&self, periods: i64) -> Self {
        self.shift_and_fill(periods, None)
    }
}

#[cfg(feature = "object")]
impl<T: PolarsObject> ChunkShiftFill<ObjectType<T>, Option<ObjectType<T>>> for ObjectChunked<T> {
    fn shift_and_fill(
        &self,
        _periods: i64,
        _fill_value: Option<ObjectType<T>>,
    ) -> ChunkedArray<ObjectType<T>> {
        todo!()
    }
}
#[cfg(feature = "object")]
impl<T: PolarsObject> ChunkShift<ObjectType<T>> for ObjectChunked<T> {
    fn shift(&self, periods: i64) -> Self {
        self.shift_and_fill(periods, None)
    }
}

#[cfg(test)]
mod test {
    use crate::prelude::*;

    #[test]
    fn test_shift() {
        let ca = Int32Chunked::new("", &[1, 2, 3]);

        // shift by 0, 1, 2, 3, 4
        let shifted = ca.shift_and_fill(0, Some(5));
        assert_eq!(Vec::from(&shifted), &[Some(1), Some(2), Some(3)]);
        let shifted = ca.shift_and_fill(1, Some(5));
        assert_eq!(Vec::from(&shifted), &[Some(5), Some(1), Some(2)]);
        let shifted = ca.shift_and_fill(2, Some(5));
        assert_eq!(Vec::from(&shifted), &[Some(5), Some(5), Some(1)]);
        let shifted = ca.shift_and_fill(3, Some(5));
        assert_eq!(Vec::from(&shifted), &[Some(5), Some(5), Some(5)]);
        let shifted = ca.shift_and_fill(4, Some(5));
        assert_eq!(Vec::from(&shifted), &[Some(5), Some(5), Some(5)]);

        // shift by -1, -2, -3, -4
        let shifted = ca.shift_and_fill(-1, Some(5));
        assert_eq!(Vec::from(&shifted), &[Some(2), Some(3), Some(5)]);
        let shifted = ca.shift_and_fill(-2, Some(5));
        assert_eq!(Vec::from(&shifted), &[Some(3), Some(5), Some(5)]);
        let shifted = ca.shift_and_fill(-3, Some(5));
        assert_eq!(Vec::from(&shifted), &[Some(5), Some(5), Some(5)]);
        let shifted = ca.shift_and_fill(-4, Some(5));
        assert_eq!(Vec::from(&shifted), &[Some(5), Some(5), Some(5)]);

        // fill with None
        let shifted = ca.shift_and_fill(1, None);
        assert_eq!(Vec::from(&shifted), &[None, Some(1), Some(2)]);
        let shifted = ca.shift_and_fill(10, None);
        assert_eq!(Vec::from(&shifted), &[None, None, None]);
        let shifted = ca.shift_and_fill(-2, None);
        assert_eq!(Vec::from(&shifted), &[Some(3), None, None]);

        // string
        let s = Series::new("a", ["a", "b", "c"]);
        let shifted = s.shift(-1);
        assert_eq!(
            Vec::from(shifted.str().unwrap()),
            &[Some("b"), Some("c"), None]
        );
    }
}