ENH: add display.max_seq_items to limit len of pprinted long sequences

pandas/core/common.py

@@ -1651,8 +1651,13 @@ def _pprint_seq(seq, _nest_lvl=0, **kwds):
     rather then calling this directly.
     """
     fmt = u"[%s]" if hasattr(seq, '__setitem__') else u"(%s)"
-    return fmt % ", ".join(pprint_thing(e, _nest_lvl + 1, **kwds)
-                                    for e in seq[:len(seq)])
+
+    nitems = get_option("max_seq_items") or len(seq)
+    body = ", ".join(pprint_thing(e, _nest_lvl + 1, **kwds)
+                                    for e in seq[:nitems])
+    if nitems < len(seq):
+        body+= ", ..."
+    return fmt % body
 
 
 def _pprint_dict(seq, _nest_lvl=0):

pandas/core/config_init.py

@@ -122,7 +122,15 @@
     if set to a float value, all float values smaller then the given threshold
     will be displayed as exactly 0 by repr and friends.
 """
+pc_max_seq_items = """
+: int or None
 
+    when pretty-printing a long sequence, no more then `max_seq_items`
+    will be printed. If items are ommitted, they will be denoted by the addition
+    of "..." to the resulting string.
+
+    If set to None, the number of items to be printed is unlimited.
+"""
 with cf.config_prefix('display'):
     cf.register_option('precision', 7, pc_precision_doc, validator=is_int)
     cf.register_option('float_format', None, float_format_doc)
@@ -149,6 +157,7 @@
     cf.register_option('expand_frame_repr', True, pc_expand_repr_doc)
     cf.register_option('line_width', 80, pc_line_width_doc)
     cf.register_option('chop_threshold', None, pc_chop_threshold_doc)
+    cf.register_option('max_seq_items', None, pc_max_seq_items)
 
 tc_sim_interactive_doc = """
 : boolean

pandas/tests/test_common.py

@@ -26,6 +26,11 @@ def test_is_sequence():
     assert(not is_seq(u"abcd"))
     assert(not is_seq(np.int64))
 
+    class A(object):
+        def __getitem__(self):
+            return 1
+
+    assert(not is_seq(A()))
 
 def test_notnull():
     assert notnull(1.)

pandas/tests/test_format.py

@@ -114,6 +114,15 @@ def test_repr_chop_threshold(self):
         with option_context("display.chop_threshold", None ):
             self.assertEqual(repr(df),  '     0    1\n0  0.1  0.5\n1  0.5 -0.1')
 
+    def test_repr_obeys_max_seq_limit(self):
+        import pandas.core.common as com
+
+        #unlimited
+        reset_option("display.max_seq_items")
+        self.assertTrue(len(com.pprint_thing(range(1000)))> 2000)
+
+        with option_context("display.max_seq_items",5):
+            self.assertTrue(len(com.pprint_thing(range(1000)))< 100)
 
     def test_repr_should_return_str(self):
         """