remove intermediate collect and use collect_reversed

pola-rs · Sep 23, 2021 · f254b5c · f254b5c
1 parent a21d2a2
commit f254b5c
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Showing 2 changed files with 19 additions and 24 deletions.
diff --git a/polars/polars-core/src/chunked_array/ops/cum_agg.rs b/polars/polars-core/src/chunked_array/ops/cum_agg.rs
@@ -60,16 +60,21 @@ where
     fn cummax(&self, reverse: bool) -> ChunkedArray<T> {
         let init = Bounded::min_value();
         let mut ca: Self = match reverse {
-            false => self.into_iter().scan(init, det_max).collect(),
-            true => self.into_iter().rev().scan(init, det_max).collect(),
+            false => self
+                .into_iter()
+                .scan(init, det_max)
+                .trust_my_length(self.len())
+                .collect_trusted(),
+            true => self
+                .into_iter()
+                .rev()
+                .scan(init, det_max)
+                .trust_my_length(self.len())
+                .collect_reversed(),
         };
 
         ca.rename(self.name());
-        if reverse {
-            ca.reverse()
-        } else {
-            ca
-        }
+        ca
     }
 
     fn cummin(&self, reverse: bool) -> ChunkedArray<T> {
@@ -85,15 +90,11 @@ where
                 .rev()
                 .scan(init, det_min)
                 .trust_my_length(self.len())
-                .collect_trusted(),
+                .collect_reversed(),
         };
 
         ca.rename(self.name());
-        if reverse {
-            ca.reverse()
-        } else {
-            ca
-        }
+        ca
     }
 
     fn cumsum(&self, reverse: bool) -> ChunkedArray<T> {
@@ -109,15 +110,11 @@ where
                 .rev()
                 .scan(init, det_sum)
                 .trust_my_length(self.len())
-                .collect_trusted(),
+                .collect_reversed(),
         };
 
         ca.rename(self.name());
-        if reverse {
-            ca.reverse()
-        } else {
-            ca
-        }
+        ca
     }
 }
 

diff --git a/polars/polars-core/src/chunked_array/ops/fill_null.rs b/polars/polars-core/src/chunked_array/ops/fill_null.rs
@@ -42,9 +42,7 @@ fn fill_backward<T>(ca: &ChunkedArray<T>) -> ChunkedArray<T>
 where
     T: PolarsNumericType,
 {
-    // TODO! improve performance. This is a double scan
-    let ca: ChunkedArray<T> = ca
-        .into_iter()
+    ca.into_iter()
         .rev()
         .scan(None, |previous, opt_v| match opt_v {
             Some(value) => {
@@ -54,8 +52,7 @@ where
             None => Some(*previous),
         })
         .trust_my_length(ca.len())
-        .collect_trusted();
-    ca.into_iter().rev().collect_trusted()
+        .collect_reversed()
 }
 
 macro_rules! impl_fill_backward {
@@ -151,6 +148,7 @@ impl ChunkFillNull for BooleanChunked {
                 Ok(out)
             }
             FillNullStrategy::Backward => {
+                // TODO: still a double scan. impl collect_reversed for boolean
                 let mut out: Self = impl_fill_backward!(self, BooleanChunked);
                 out.rename(self.name());
                 Ok(out)