polars_ops/frame/join/
general.rs

1use polars_utils::format_pl_smallstr;
2
3use super::*;
4use crate::series::coalesce_columns;
5
6pub fn _join_suffix_name(name: &str, suffix: &str) -> PlSmallStr {
7    format_pl_smallstr!("{name}{suffix}")
8}
9
10fn get_suffix(suffix: Option<PlSmallStr>) -> PlSmallStr {
11    suffix.unwrap_or_else(|| PlSmallStr::from_static("_right"))
12}
13
14/// Renames the columns on the right to not clash with the left using a specified or otherwise default suffix
15/// and then merges the right dataframe into the left
16#[doc(hidden)]
17pub fn _finish_join(
18    mut df_left: DataFrame,
19    mut df_right: DataFrame,
20    suffix: Option<PlSmallStr>,
21) -> PolarsResult<DataFrame> {
22    let mut left_names = PlHashSet::with_capacity(df_left.width());
23
24    df_left.get_columns().iter().for_each(|series| {
25        left_names.insert(series.name());
26    });
27
28    let mut rename_strs = Vec::with_capacity(df_right.width());
29    let right_names = df_right.schema();
30
31    for name in right_names.iter_names() {
32        if left_names.contains(name) {
33            rename_strs.push(name.clone())
34        }
35    }
36
37    let suffix = get_suffix(suffix);
38
39    df_right.rename_many(rename_strs.iter().map(|name| {
40        (
41            name.as_str(),
42            _join_suffix_name(name.as_str(), suffix.as_str()),
43        )
44    }))?;
45
46    drop(left_names);
47    // Safety: IR resolving should guarantee this passes
48    unsafe { df_left.hstack_mut_unchecked(df_right.get_columns()) };
49    Ok(df_left)
50}
51
52pub fn _coalesce_full_join(
53    mut df: DataFrame,
54    keys_left: &[PlSmallStr],
55    keys_right: &[PlSmallStr],
56    suffix: Option<PlSmallStr>,
57    df_left: &DataFrame,
58) -> DataFrame {
59    // No need to allocate the schema because we already
60    // know for certain that the column name for left is `name`
61    // and for right is `name + suffix`
62    let schema_left = if keys_left == keys_right {
63        Arc::new(Schema::default())
64    } else {
65        df_left.schema().clone()
66    };
67
68    let schema = df.schema().clone();
69    let mut to_remove = Vec::with_capacity(keys_right.len());
70
71    // SAFETY: we maintain invariants.
72    let columns = unsafe { df.get_columns_mut() };
73    let suffix = get_suffix(suffix);
74    for (l, r) in keys_left.iter().zip(keys_right.iter()) {
75        let pos_l = schema.get_full(l.as_str()).unwrap().0;
76
77        let r = if l == r || schema_left.contains(r.as_str()) {
78            _join_suffix_name(r.as_str(), suffix.as_str())
79        } else {
80            r.clone()
81        };
82        let pos_r = schema.get_full(&r).unwrap().0;
83
84        let l = columns[pos_l].clone();
85        let r = columns[pos_r].clone();
86
87        columns[pos_l] = coalesce_columns(&[l, r]).unwrap();
88        to_remove.push(pos_r);
89    }
90    // sort in reverse order, so the indexes remain correct if we remove.
91    to_remove.sort_by(|a, b| b.cmp(a));
92    for pos in to_remove {
93        let _ = columns.remove(pos);
94    }
95    df.clear_schema();
96    df
97}
98
99#[cfg(feature = "chunked_ids")]
100pub(crate) fn create_chunked_index_mapping(chunks: &[ArrayRef], len: usize) -> Vec<ChunkId> {
101    let mut vals = Vec::with_capacity(len);
102
103    for (chunk_i, chunk) in chunks.iter().enumerate() {
104        vals.extend(
105            (0..chunk.len()).map(|array_i| ChunkId::store(chunk_i as IdxSize, array_i as IdxSize)),
106        )
107    }
108
109    vals
110}
polars_ops/frame/join/general.rs

polars_ops/frame/join/
general.rs
