improve categorical::full_null (#2706)

pola-rs · Feb 20, 2022 · f741284 · f741284
1 parent 5fe8aeb
commit f741284
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Showing 2 changed files with 9 additions and 5 deletions.
diff --git a/polars/polars-core/src/chunked_array/logical/categorical/builder.rs b/polars/polars-core/src/chunked_array/logical/categorical/builder.rs
@@ -46,6 +46,13 @@ pub enum RevMapping {
     Local(Utf8Array<i64>),
 }
 
+impl Default for RevMapping {
+    fn default() -> Self {
+        let slice: &[Option<&str>] = &[];
+        RevMapping::Local(Utf8Array::<i64>::from(slice))
+    }
+}
+
 #[allow(clippy::len_without_is_empty)]
 impl RevMapping {
     /// Get the length of the [`RevMapping`]

diff --git a/polars/polars-core/src/chunked_array/logical/categorical/ops/full.rs b/polars/polars-core/src/chunked_array/logical/categorical/ops/full.rs
@@ -2,10 +2,7 @@ use super::*;
 
 impl CategoricalChunked {
     pub fn full_null(name: &str, length: usize) -> CategoricalChunked {
-        // TODO! implement proper, can be faster
-        let mut builder = CategoricalChunkedBuilder::new(name, length);
-        let iter = (0..length).map(|_| None);
-        builder.drain_iter(iter);
-        builder.finish()
+        let cats = UInt32Chunked::full_null(name, length);
+        CategoricalChunked::from_cats_and_rev_map(cats, Arc::new(RevMapping::default()))
     }
 }