Add option --exclude-dependencies for "pip freeze" and "pip list"

src/pip/_internal/commands/freeze.py

@@ -81,6 +81,12 @@ def add_options(self) -> None:
             action="store_true",
             help="Exclude editable package from output.",
         )
+        self.cmd_opts.add_option(
+            "--exclude-dependencies",
+            dest="exclude_dependencies",
+            action="store_true",
+            help="Exclude dependency packages from output.",
+        )
         self.cmd_opts.add_option(cmdoptions.list_exclude())
 
         self.parser.insert_option_group(0, self.cmd_opts)
@@ -103,6 +109,7 @@ def run(self, options: Values, args: List[str]) -> int:
             isolated=options.isolated_mode,
             skip=skip,
             exclude_editable=options.exclude_editable,
+            exclude_dependencies=options.exclude_dependencies,
         ):
             sys.stdout.write(line + "\n")
         return SUCCESS

src/pip/_internal/commands/list.py

@@ -129,6 +129,12 @@ def add_options(self) -> None:
             help="Include editable package from output.",
             default=True,
         )
+        self.cmd_opts.add_option(
+            "--exclude-dependencies",
+            dest="exclude_dependencies",
+            action="store_true",
+            help="Exclude dependency packages from output.",
+        )
         self.cmd_opts.add_option(cmdoptions.list_exclude())
         index_opts = cmdoptions.make_option_group(cmdoptions.index_group, self.parser)
 
@@ -176,6 +182,7 @@ def run(self, options: Values, args: List[str]) -> int:
                 user_only=options.user,
                 editables_only=options.editable,
                 include_editables=options.include_editable,
+                exclude_dependencies=options.exclude_dependencies,
                 skip=skip,
             )
         ]

src/pip/_internal/metadata/base.py

@@ -649,6 +649,7 @@ def iter_installed_distributions(
         include_editables: bool = True,
         editables_only: bool = False,
         user_only: bool = False,
+        exclude_dependencies: bool = False,
     ) -> Iterator[BaseDistribution]:
         """Return a list of installed distributions.
 
@@ -665,8 +666,20 @@ def iter_installed_distributions(
         :param editables_only: If True, only report editables.
         :param user_only: If True, only report installations in the user
         site directory.
+        :param exclude_dependencies: If True, dont't report distributions
+        that are dependencies of other installed distributions.
         """
-        it = self.iter_all_distributions()
+        if exclude_dependencies:
+            dists = list(self.iter_all_distributions())
+            it = iter(dists)
+            dep_keys = {
+                canonicalize_name(dep.name)
+                for dist in dists
+                for dep in (dist.iter_dependencies() or ())
+            }
+            it = (d for d in it if d.canonical_name not in dep_keys)
+        else:
+            it = self.iter_all_distributions()
         if local_only:
             it = (d for d in it if d.local)
         if not include_editables:

src/pip/_internal/operations/freeze.py

@@ -30,6 +30,7 @@ def freeze(
     paths: Optional[List[str]] = None,
     isolated: bool = False,
     exclude_editable: bool = False,
+    exclude_dependencies: bool = False,
     skip: Container[str] = (),
 ) -> Generator[str, None, None]:
     installations: Dict[str, FrozenRequirement] = {}
@@ -38,6 +39,7 @@ def freeze(
         local_only=local_only,
         skip=(),
         user_only=user_only,
+        exclude_dependencies=exclude_dependencies,
     )
     for dist in dists:
         req = FrozenRequirement.from_dist(dist)