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
#[cfg(feature = "dtype-categorical")]
use crate::chunked_array::categorical::CategoricalChunkedBuilder;
use crate::prelude::*;
use arrow::compute::cast;
use std::convert::TryFrom;
pub(crate) fn cast_chunks(chunks: &[ArrayRef], dtype: &DataType) -> Result<Vec<ArrayRef>> {
let chunks = chunks
.iter()
.map(|arr| cast::cast(arr.as_ref(), &dtype.to_arrow()))
.map(|arr| arr.map(|x| x.into()))
.collect::<arrow::error::Result<Vec<_>>>()?;
Ok(chunks)
}
fn cast_impl(name: &str, chunks: &[ArrayRef], dtype: &DataType) -> Result<Series> {
let chunks = cast_chunks(chunks, &dtype.to_physical())?;
let out = Series::try_from((name, chunks))?;
use DataType::*;
let out = match dtype {
Date | Datetime => out.into_date(),
#[cfg(feature = "dtype-time")]
Time => out.into_time(),
_ => out,
};
Ok(out)
}
#[cfg(feature = "dtype-categorical")]
impl ChunkCast for CategoricalChunked {
fn cast(&self, data_type: &DataType) -> Result<Series> {
match data_type {
DataType::Utf8 => {
let mapping = &**self.categorical_map.as_ref().expect("should be set");
let mut builder = Utf8ChunkedBuilder::new(self.name(), self.len(), self.len() * 5);
let f = |idx: u32| mapping.get(idx);
if self.null_count() == 0 {
self.into_no_null_iter()
.for_each(|idx| builder.append_value(f(idx)));
} else {
self.into_iter().for_each(|opt_idx| {
builder.append_option(opt_idx.map(f));
});
}
let ca = builder.finish();
Ok(ca.into_series())
}
DataType::UInt32 => {
let ca = UInt32Chunked::new_from_chunks(self.name(), self.chunks.clone());
Ok(ca.into_series())
}
#[cfg(feature = "dtype-categorical")]
DataType::Categorical => Ok(self.clone().into_series()),
_ => cast_impl(self.name(), &self.chunks, data_type),
}
}
}
impl<T> ChunkCast for ChunkedArray<T>
where
T: PolarsNumericType,
{
fn cast(&self, data_type: &DataType) -> Result<Series> {
match (self.dtype(), data_type) {
#[cfg(feature = "dtype-categorical")]
(DataType::UInt32, DataType::Categorical)
| (DataType::Categorical, DataType::Categorical) => {
let ca = CategoricalChunked::new_from_chunks(self.name(), self.chunks.clone())
.set_state(self);
Ok(ca.into_series())
}
_ => cast_impl(self.name(), &self.chunks, data_type),
}
}
}
impl ChunkCast for Utf8Chunked {
fn cast(&self, data_type: &DataType) -> Result<Series> {
match data_type {
#[cfg(feature = "dtype-categorical")]
DataType::Categorical => {
let iter = self.into_iter();
let mut builder = CategoricalChunkedBuilder::new(self.name(), self.len());
builder.from_iter(iter);
let ca = builder.finish();
Ok(ca.into_series())
}
_ => cast_impl(self.name(), &self.chunks, data_type),
}
}
}
fn boolean_to_utf8(ca: &BooleanChunked) -> Utf8Chunked {
ca.into_iter()
.map(|opt_b| match opt_b {
Some(true) => Some("true"),
Some(false) => Some("false"),
None => None,
})
.collect()
}
impl ChunkCast for BooleanChunked {
fn cast(&self, data_type: &DataType) -> Result<Series> {
if matches!(data_type, DataType::Utf8) {
let mut ca = boolean_to_utf8(self);
ca.rename(self.name());
Ok(ca.into_series())
} else {
cast_impl(self.name(), &self.chunks, data_type)
}
}
}
fn cast_inner_list_type(list: &ListArray<i64>, child_type: &DataType) -> Result<ArrayRef> {
let child = list.values();
let offsets = list.offsets();
let child = cast::cast(child.as_ref(), &child_type.to_arrow())?.into();
let data_type = ListArray::<i64>::default_datatype(child_type.to_arrow());
let list = ListArray::from_data(data_type, offsets.clone(), child, list.validity().cloned());
Ok(Arc::new(list) as ArrayRef)
}
impl ChunkCast for ListChunked {
fn cast(&self, data_type: &DataType) -> Result<Series> {
match data_type {
DataType::List(child_type) => {
let chunks = self
.downcast_iter()
.map(|list| cast_inner_list_type(list, &**child_type))
.collect::<Result<_>>()?;
let ca = ListChunked::new_from_chunks(self.name(), chunks);
Ok(ca.into_series())
}
_ => Err(PolarsError::ComputeError("Cannot cast list type".into())),
}
}
}
#[cfg(test)]
mod test {
use crate::prelude::*;
#[test]
fn test_cast_list() -> Result<()> {
let mut builder = ListPrimitiveChunkedBuilder::<Int32Type>::new("a", 10, 10);
builder.append_slice(Some(&[1i32, 2, 3]));
builder.append_slice(Some(&[1i32, 2, 3]));
let ca = builder.finish();
let new = ca.cast(&DataType::List(DataType::Float64.into()))?;
assert_eq!(new.dtype(), &DataType::List(DataType::Float64.into()));
Ok(())
}
#[test]
#[cfg(feature = "dtype-categorical")]
fn test_cast_noop() {
let ca = Utf8Chunked::new_from_slice("foo", &["bar", "ham"]);
let out = ca.cast(&DataType::Categorical).unwrap();
let out = out.cast(&DataType::Categorical).unwrap();
assert_eq!(out.dtype(), &DataType::Categorical)
}
}