numpy · a-sajjad72 · Jun 30, 2025 · Jun 30, 2025 · Jun 30, 2025 · Jul 1, 2025
diff --git a/numpy/lib/_npyio_impl.py b/numpy/lib/_npyio_impl.py
@@ -108,8 +108,14 @@ def zipfile_factory(file, *args, **kwargs):
     if not hasattr(file, 'read'):
         file = os.fspath(file)
     import zipfile
-    kwargs['allowZip64'] = True
-    return zipfile.ZipFile(file, *args, **kwargs)
+
+    # Handle compression parameters
+    compresslevel = kwargs.pop('compresslevel', None)
+    compression = kwargs.pop('compression', zipfile.ZIP_STORED)
+
+    # Modern Python versions support compresslevel
+    return zipfile.ZipFile(file, *args, compression=compression,
+                           compresslevel=compresslevel, **kwargs)
 
 
 @set_module('numpy.lib.npyio')
@@ -686,13 +692,15 @@ def savez(file, *args, allow_pickle=True, **kwds):
     _savez(file, args, kwds, False, allow_pickle=allow_pickle)
 
 
-def _savez_compressed_dispatcher(file, *args, allow_pickle=True, **kwds):
+def _savez_compressed_dispatcher(file, *args, allow_pickle=True,
+                                 zipfile_kwargs=None, **kwds):
     yield from args
     yield from kwds.values()
 
 
 @array_function_dispatch(_savez_compressed_dispatcher)
-def savez_compressed(file, *args, allow_pickle=True, **kwds):
+def savez_compressed(file, *args, allow_pickle=True,
+                     zipfile_kwargs=None, **kwds):
     """
     Save several arrays into a single file in compressed ``.npz`` format.
 
@@ -721,6 +729,10 @@ def savez_compressed(file, *args, allow_pickle=True, **kwds):
         require libraries that are not available, and not all pickled data is
         compatible between different versions of Python).
         Default: True
+    zipfile_kwargs : dict, optional
+        Dictionary of keyword arguments forwarded directly to
+        ``zipfile.ZipFile`` (e.g. ``compression``, ``compresslevel``).
+        By default, ``compression`` is set to ``ZIP_DEFLATED``.
     kwds : Keyword arguments, optional
         Arrays to save to the file. Each array will be saved to the
         output file with its corresponding keyword name.
@@ -763,12 +775,12 @@ def savez_compressed(file, *args, allow_pickle=True, **kwds):
     True
 
     """
-    _savez(file, args, kwds, True, allow_pickle=allow_pickle)
+    _savez(file, args, kwds, True, allow_pickle=allow_pickle,
+           zipfile_kwargs=zipfile_kwargs)
 
 
-def _savez(file, args, kwds, compress, allow_pickle=True, pickle_kwargs=None):
-    # Import is postponed to here since zipfile depends on gzip, an optional
-    # component of the so-called standard library.
+def _savez(file, args, kwds, compress, allow_pickle=True, pickle_kwargs=None,
+           zipfile_kwargs=None):
     import zipfile
 
     if not hasattr(file, 'write'):
@@ -784,12 +796,88 @@ def _savez(file, args, kwds, compress, allow_pickle=True, pickle_kwargs=None):
                 f"Cannot use un-named variables and keyword {key}")
         namedict[key] = val
 
-    if compress:
-        compression = zipfile.ZIP_DEFLATED
+    # Prepare ZipFile keyword arguments
+    if zipfile_kwargs is None:
+        zipfile_kwargs = {}
+
+    # Default behaviour: use DEFLATED for the compressed variant, STORED
+    # otherwise – unless the user explicitly asked for something else.
+    comp = zipfile_kwargs.get("compression")
+    if comp is None:
+        comp = zipfile.ZIP_DEFLATED if compress else zipfile.ZIP_STORED
     else:
-        compression = zipfile.ZIP_STORED
+        # Translate textual aliases such as ``"deflated"`` to their integer
+        # counterparts.  Accepting the textual form mirrors the behaviour of
+        # ``zipfile.ZipFile`` and provides a more friendly public API.
+        if isinstance(comp, str):
+            _str_to_const = {
+                "stored": zipfile.ZIP_STORED,
+                "deflated": zipfile.ZIP_DEFLATED,
+            }
+            if hasattr(zipfile, "ZIP_BZIP2"):
+                _str_to_const["bzip2"] = zipfile.ZIP_BZIP2
+            if hasattr(zipfile, "ZIP_LZMA"):
+                _str_to_const["lzma"] = zipfile.ZIP_LZMA
+
+            key = comp.lower()
+            if key not in _str_to_const:
+                raise ValueError(
+                    f"Unknown compression method: {comp!r}. "
+                    f"Valid options: {list(_str_to_const)}"
+                )
+            comp = _str_to_const[key]
+        elif isinstance(comp, int):
+            # Verify that the provided integer constant is supported by the
+            # runtime Python build.
+            _valid_ints = {zipfile.ZIP_STORED, zipfile.ZIP_DEFLATED}
+            if hasattr(zipfile, "ZIP_BZIP2"):
+                _valid_ints.add(zipfile.ZIP_BZIP2)
+            if hasattr(zipfile, "ZIP_LZMA"):
+                _valid_ints.add(zipfile.ZIP_LZMA)
+
+            if comp not in _valid_ints:
+                raise ValueError(
+                    f"Unknown compression method: {comp}. "
+                    f"Valid options: {sorted(_valid_ints)}"
+                )
+        else:
+            raise TypeError(
+                "compression must be an int (zipfile constant) or a str "
+                "specifying the method"
+            )
+
+    # Persist the (possibly normalised) compression constant back into kwargs
+    zipfile_kwargs["compression"] = comp
+
+    # Validate ``compresslevel`` – ignore if the user passed ``None``.
+    cl = zipfile_kwargs.pop("compresslevel", None)
+    if cl is not None:
+        if not isinstance(cl, int):
+            raise ValueError("compresslevel must be an integer or None")
+
+        if comp == zipfile.ZIP_STORED:
+            raise ValueError(
+                "compresslevel is not applicable when using ZIP_STORED."
+            )
+
+        def _in_range(minv: int, maxv: int) -> bool:
+            return minv <= cl <= maxv
+
+        if comp == zipfile.ZIP_DEFLATED and not _in_range(0, 9):
+            raise ValueError("For DEFLATED, compresslevel must be between 0 and 9.")
+        if (hasattr(zipfile, "ZIP_BZIP2") and comp == zipfile.ZIP_BZIP2
+                and not _in_range(1, 9)):
+            raise ValueError("For BZIP2, compresslevel must be between 1 and 9.")
+        if (hasattr(zipfile, "ZIP_LZMA") and comp == zipfile.ZIP_LZMA
+                and not _in_range(0, 9)):
+            raise ValueError("For LZMA, compresslevel must be between 0 and 9.")
+
+        # Store the validated compresslevel back into kwargs
+        zipfile_kwargs["compresslevel"] = cl
+
+    # Create the ZipFile object
+    zipf = zipfile_factory(file, mode="w", **zipfile_kwargs)
 
-    zipf = zipfile_factory(file, mode="w", compression=compression)
     try:
         for key, val in namedict.items():
             fname = key + '.npy'