[BUG] handle } in line delimited json

asv_bench/benchmarks/packers.py

@@ -547,6 +547,33 @@ def remove(self, f):
             pass
 
 
+class packers_write_json_lines(object):
+    goal_time = 0.2
+
+    def setup(self):
+        self.f = '__test__.msg'
+        self.N = 100000
+        self.C = 5
+        self.index = date_range('20000101', periods=self.N, freq='H')
+        self.df = DataFrame(dict([('float{0}'.format(i), randn(self.N)) for i in range(self.C)]), index=self.index)
+        self.df2 = DataFrame(dict([('float{0}'.format(i), randn(self.N)) for i in range(self.C)]), index=self.index)
+        self.df2['object'] = [('%08x' % randrange((16 ** 8))) for _ in range(self.N)]
+        self.remove(self.f)
+        self.df.index = np.arange(self.N)
+
+    def time_packers_write_json_lines(self):
+        self.df.to_json(self.f, orient="records", lines=True)
+
+    def teardown(self):
+        self.remove(self.f)
+
+    def remove(self, f):
+        try:
+            os.remove(self.f)
+        except:
+            pass
+
+
 class packers_write_json_T(object):
     goal_time = 0.2
 

doc/source/whatsnew/v0.19.1.txt

@@ -45,3 +45,4 @@ Bug Fixes
 
 - Bug in ``pd.concat`` where names of the ``keys`` were not propagated to the resulting ``MultiIndex`` (:issue:`14252`)
 - Bug in ``MultiIndex.set_levels`` where illegal level values were still set after raising an error (:issue:`13754`)
+- Bug in ``DataFrame.to_json`` where ``lines=True`` and a value contained a ``}`` character (:issue:`14391`)

pandas/io/json.py

@@ -607,14 +607,19 @@ def _convert_to_line_delimits(s):
     s = s[1:-1]
     num_open_brackets_seen = 0
     commas_to_replace = []
+    in_quotes = False
     for idx, char in enumerate(s):              # iter through to find all
-        if char == ',':                         # commas that should be \n
-            if num_open_brackets_seen == 0:
+        if char == '"' and idx > 0 and s[idx - 1] != '\\':
+            in_quotes = ~in_quotes
+        elif char == ',':                         # commas that should be \n
+            if num_open_brackets_seen == 0 and not in_quotes:
                 commas_to_replace.append(idx)
         elif char == '{':
-            num_open_brackets_seen += 1
+            if not in_quotes:
+                num_open_brackets_seen += 1
         elif char == '}':
-            num_open_brackets_seen -= 1
+            if not in_quotes:
+                num_open_brackets_seen -= 1
     s_arr = np.array(list(s))                  # Turn to an array to set
     s_arr[commas_to_replace] = '\n'            # all commas at once.
     s = ''.join(s_arr)

pandas/io/tests/json/test_pandas.py

@@ -962,6 +962,12 @@ def test_to_jsonl(self):
         expected = '{"a":1,"b":2}\n{"a":1,"b":2}'
         self.assertEqual(result, expected)
 
+        df = DataFrame([["foo}", "bar"], ['foo"', "bar"]], columns=['a', 'b'])
+        result = df.to_json(orient="records", lines=True)
+        expected = '{"a":"foo}","b":"bar"}\n{"a":"foo\\"","b":"bar"}'
+        self.assertEqual(result, expected)
+        assert_frame_equal(pd.read_json(result, lines=True), df)
+
     def test_latin_encoding(self):
         if compat.PY2:
             self.assertRaisesRegexp(