PERF: Use generator expression for Blocks.replace_list

asv_bench/benchmarks/series_methods.py

@@ -401,4 +401,34 @@ def time_to_numpy_copy(self):
         self.ser.to_numpy(copy=True)
 
 
+class Replace:
+
+    param_names = ["num_to_replace"]
+    params = [100, 1000]
+
+    def setup(self, num_to_replace):
+        N = 1_000_000
+        self.arr = np.random.randn(N)
+        self.arr1 = self.arr.copy()
+        np.random.shuffle(self.arr1)
+        self.ser = Series(self.arr)
+
+        self.to_replace_list = np.random.choice(self.arr, num_to_replace)
+        self.values_list = np.random.choice(self.arr1, num_to_replace)
+
+        self.replace_dict = dict(zip(self.to_replace_list, self.values_list))
+
+    def time_replace_dict(self, num_to_replace):
+        self.ser.replace(self.replace_dict)
+
+    def peakmem_replace_dict(self, num_to_replace):
+        self.ser.replace(self.replace_dict)
+
+    def time_replace_list(self, num_to_replace):
+        self.ser.replace(self.to_replace_list, self.values_list)
+
+    def peakmem_replace_list(self, num_to_replace):
+        self.ser.replace(self.to_replace_list, self.values_list)
+
+
 from .pandas_vb_common import setup  # noqa: F401 isort:skip

pandas/core/internals/blocks.py

@@ -663,22 +663,25 @@ def replace_list(
         if is_string_dtype(values.dtype):
             # Calculate the mask once, prior to the call of comp
             # in order to avoid repeating the same computations
-            mask = ~isna(values)
-            masks = [
-                compare_or_regex_search(values, s[0], regex=regex, mask=mask)
+            na_mask = ~isna(values)
+            masks = (
+                extract_bool_array(
+                    compare_or_regex_search(values, s[0], regex=regex, mask=na_mask)
+                )
                 for s in pairs
-            ]
+            )
         else:
             # GH#38086 faster if we know we dont need to check for regex
-            masks = [missing.mask_missing(values, s[0]) for s in pairs]
+            masks = (
+                extract_bool_array(missing.mask_missing(values, s[0])) for s in pairs
+            )
 
         # error: Argument 1 to "extract_bool_array" has incompatible type
         # "Union[ExtensionArray, ndarray, bool]"; expected "Union[ExtensionArray,
         # ndarray]"
-        masks = [extract_bool_array(x) for x in masks]  # type: ignore[arg-type]
-
+        # masks = [extract_bool_array(x) for x in masks]  # type: ignore[arg-type]
         rb = [self if inplace else self.copy()]
-        for i, (src, dest) in enumerate(pairs):
+        for i, ((src, dest), mask) in enumerate(zip(pairs, masks)):
             convert = i == src_len  # only convert once at the end
             new_rb: list[Block] = []
 
@@ -687,9 +690,9 @@ def replace_list(
             # where to index into the mask
             for blk_num, blk in enumerate(rb):
                 if len(rb) == 1:
-                    m = masks[i]
+                    m = mask
                 else:
-                    mib = masks[i]
+                    mib = mask
                     assert not isinstance(mib, bool)
                     m = mib[blk_num : blk_num + 1]