PERF: HDFStore has faster __unicode__, new info() method with old behavior.

__unicode__ now only returns file path info, not (expensive) details on all existing keys.

Author: Kiv

asv_bench/benchmarks/hdfstore_bench.py

@@ -90,6 +90,15 @@ def time_query_store_table(self):
         stop = self.df2.index[15000]
         self.store.select('table', where="index > start and index < stop")
 
+    def time_store_repr(self):
+        repr(self.store)
+
+    def time_store_str(self):
+        str(self.store)
+
+    def time_store_info(self):
+        self.store.info()
+
 
 class HDF5Panel(object):
     goal_time = 0.2

doc/source/api.rst

@@ -99,6 +99,7 @@ HDFStore: PyTables (HDF5)
    HDFStore.append
    HDFStore.get
    HDFStore.select
+   HDFStore.info
 
 Feather
 ~~~~~~~

doc/source/whatsnew/v0.21.0.txt

@@ -49,6 +49,8 @@ Backwards incompatible API changes
 - Accessing a non-existent attribute on a closed :class:`HDFStore` will now
   raise an ``AttributeError`` rather than a ``ClosedFileError`` (:issue:`16301`)
 
+- :class:`pandas.HDFStore`'s string representation is now faster and less detailed. For the previous behavior, use ``pandas.HDFStore.info()``. (:issue:`16503`).
+
 .. _whatsnew_0210.api:
 
 Other API Changes

pandas/io/pytables.py

@@ -494,32 +494,7 @@ def __len__(self):
         return len(self.groups())
 
     def __unicode__(self):
-        output = '%s\nFile path: %s\n' % (type(self), pprint_thing(self._path))
-        if self.is_open:
-            lkeys = sorted(list(self.keys()))
-            if len(lkeys):
-                keys = []
-                values = []
-
-                for k in lkeys:
-                    try:
-                        s = self.get_storer(k)
-                        if s is not None:
-                            keys.append(pprint_thing(s.pathname or k))
-                            values.append(
-                                pprint_thing(s or 'invalid_HDFStore node'))
-                    except Exception as detail:
-                        keys.append(k)
-                        values.append("[invalid_HDFStore node: %s]"
-                                      % pprint_thing(detail))
-
-                output += adjoin(12, keys, values)
-            else:
-                output += 'Empty'
-        else:
-            output += "File is CLOSED"
-
-        return output
+        return '%s\nFile path: %s\n' % (type(self), pprint_thing(self._path))
 
     def __enter__(self):
         return self
@@ -1161,6 +1136,37 @@ def copy(self, file, mode='w', propindexes=True, keys=None, complib=None,
 
         return new_store
 
+    def info(self):
+        """return detailed information on the store
+        .. versionadded:: 0.21.0
+        """
+        output = '%s\nFile path: %s\n' % (type(self), pprint_thing(self._path))
+        if self.is_open:
+            lkeys = sorted(list(self.keys()))
+            if len(lkeys):
+                keys = []
+                values = []
+
+                for k in lkeys:
+                    try:
+                        s = self.get_storer(k)
+                        if s is not None:
+                            keys.append(pprint_thing(s.pathname or k))
+                            values.append(
+                                pprint_thing(s or 'invalid_HDFStore node'))
+                    except Exception as detail:
+                        keys.append(k)
+                        values.append("[invalid_HDFStore node: %s]"
+                                      % pprint_thing(detail))
+
+                output += adjoin(12, keys, values)
+            else:
+                output += 'Empty'
+        else:
+            output += "File is CLOSED"
+
+        return output
+
     # private methods ######
     def _check_if_open(self):
         if not self.is_open:

pandas/tests/io/test_pytables.py

@@ -387,6 +387,7 @@ def test_repr(self):
 
         with ensure_clean_store(self.path) as store:
             repr(store)
+            store.info()
             store['a'] = tm.makeTimeSeries()
             store['b'] = tm.makeStringSeries()
             store['c'] = tm.makeDataFrame()
@@ -418,8 +419,9 @@ def test_repr(self):
             # make a random group in hdf space
             store._handle.create_group(store._handle.root, 'bah')
 
-            repr(store)
-            str(store)
+            assert store.filename in repr(store)
+            assert store.filename in str(store)
+            store.info()
 
         # storers
         with ensure_clean_store(self.path) as store:
@@ -4371,11 +4373,11 @@ def test_multiple_open_close(self):
 
             # single
             store = HDFStore(path)
-            assert 'CLOSED' not in str(store)
+            assert 'CLOSED' not in store.info()
             assert store.is_open
 
             store.close()
-            assert 'CLOSED' in str(store)
+            assert 'CLOSED' in store.info()
             assert not store.is_open
 
         with ensure_clean_path(self.path) as path:
@@ -4396,20 +4398,20 @@ def f():
                 store1 = HDFStore(path)
                 store2 = HDFStore(path)
 
-                assert 'CLOSED' not in str(store1)
-                assert 'CLOSED' not in str(store2)
+                assert 'CLOSED' not in store1.info()
+                assert 'CLOSED' not in store2.info()
                 assert store1.is_open
                 assert store2.is_open
 
                 store1.close()
-                assert 'CLOSED' in str(store1)
+                assert 'CLOSED' in store1.info()
                 assert not store1.is_open
-                assert 'CLOSED' not in str(store2)
+                assert 'CLOSED' not in store2.info()
                 assert store2.is_open
 
                 store2.close()
-                assert 'CLOSED' in str(store1)
-                assert 'CLOSED' in str(store2)
+                assert 'CLOSED' in store1.info()
+                assert 'CLOSED' in store2.info()
                 assert not store1.is_open
                 assert not store2.is_open
 
@@ -4420,11 +4422,11 @@ def f():
                 store2 = HDFStore(path)
                 store2.append('df2', df)
                 store2.close()
-                assert 'CLOSED' in str(store2)
+                assert 'CLOSED' in store2.info()
                 assert not store2.is_open
 
                 store.close()
-                assert 'CLOSED' in str(store)
+                assert 'CLOSED' in store.info()
                 assert not store.is_open
 
                 # double closing
@@ -4433,11 +4435,11 @@ def f():
 
                 store2 = HDFStore(path)
                 store.close()
-                assert 'CLOSED' in str(store)
+                assert 'CLOSED' in store.info()
                 assert not store.is_open
 
                 store2.close()
-                assert 'CLOSED' in str(store2)
+                assert 'CLOSED' in store2.info()
                 assert not store2.is_open
 
         # ops on a closed store
@@ -4784,9 +4786,10 @@ def test_categorical(self):
             tm.assert_frame_equal(result, df2)
 
             # Make sure the metadata is OK
-            assert '/df2   ' in str(store)
-            assert '/df2/meta/values_block_0/meta' in str(store)
-            assert '/df2/meta/values_block_1/meta' in str(store)
+            info = store.info()
+            assert '/df2   ' in info
+            assert '/df2/meta/values_block_0/meta' in info
+            assert '/df2/meta/values_block_1/meta' in info
 
             # unordered
             s = Series(Categorical(['a', 'b', 'b', 'a', 'a', 'c'], categories=[