Issue 1:
Code Sample, a copy-pastable example if possible

Executing

import pandas as pd

df = pd.DataFrame({'a':[pd.Timestamp('2010-02-01'),
pd.Timestamp('2010-02-04'),
pd.Timestamp('2010-02-05'),
pd.Timestamp('2010-02-06')],
'b':[9,5,4,3], 'c':[5,3,4,2], 'd':[1,2,3,4]})

def fun(x):
return (1,2)

df.apply(fun, axis=1)

raises an exception

---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
/Users/wilmat01/anaconda/lib/python3.6/site-packages/pandas/core/internals.py in create_block_manager_from_arrays(arrays, names, axes)
4309 blocks = form_blocks(arrays, names, axes)
-> 4310 mgr = BlockManager(blocks, axes)
4311 mgr._consolidate_inplace()

/Users/wilmat01/anaconda/lib/python3.6/site-packages/pandas/core/internals.py in __init__(self, blocks, axes, do_integrity_check, fastpath)
2794 if do_integrity_check:
-> 2795 self._verify_integrity()
2796

/Users/wilmat01/anaconda/lib/python3.6/site-packages/pandas/core/internals.py in _verify_integrity(self)
3005 if block._verify_integrity and block.shape[1:] != mgr_shape[1:]:
-> 3006 construction_error(tot_items, block.shape[1:], self.axes)
3007 if len(self.items) != tot_items:

/Users/wilmat01/anaconda/lib/python3.6/site-packages/pandas/core/internals.py in construction_error(tot_items, block_shape, axes, e)
4279 raise ValueError("Shape of passed values is {0}, indices imply {1}".format(
-> 4280 passed, implied))
4281

ValueError: Shape of passed values is (4, 2), indices imply (4, 4)

During handling of the above exception, another exception occurred:

ValueError Traceback (most recent call last)
<ipython-input-26-7b305f7b3474> in <module>()
8 return (1,2)
9
---> 10 df.apply(fun, axis=1)

/Users/wilmat01/anaconda/lib/python3.6/site-packages/pandas/core/frame.py in apply(self, func, axis, broadcast, raw, reduce, args, **kwds)
4260 f, axis,
4261 reduce=reduce,
-> 4262 ignore_failures=ignore_failures)
4263 else:
4264 return self._apply_broadcast(f, axis)

/Users/wilmat01/anaconda/lib/python3.6/site-packages/pandas/core/frame.py in _apply_standard(self, func, axis, ignore_failures, reduce)
4373 index = None
4374
-> 4375 result = self._constructor(data=results, index=index)
4376 result.columns = res_index
4377

/Users/wilmat01/anaconda/lib/python3.6/site-packages/pandas/core/frame.py in __init__(self, data, index, columns, dtype, copy)
273 dtype=dtype, copy=copy)
274 elif isinstance(data, dict):
--> 275 mgr = self._init_dict(data, index, columns, dtype=dtype)
276 elif isinstance(data, ma.MaskedArray):
277 import numpy.ma.mrecords as mrecords

/Users/wilmat01/anaconda/lib/python3.6/site-packages/pandas/core/frame.py in _init_dict(self, data, index, columns, dtype)
409 arrays = [data[k] for k in keys]
410
--> 411 return _arrays_to_mgr(arrays, data_names, index, columns, dtype=dtype)
412
413 def _init_ndarray(self, values, index, columns, dtype=None, copy=False):

/Users/wilmat01/anaconda/lib/python3.6/site-packages/pandas/core/frame.py in _arrays_to_mgr(arrays, arr_names, index, columns, dtype)
5504 axes = [_ensure_index(columns), _ensure_index(index)]
5505
-> 5506 return create_block_manager_from_arrays(arrays, arr_names, axes)
5507
5508

/Users/wilmat01/anaconda/lib/python3.6/site-packages/pandas/core/internals.py in create_block_manager_from_arrays(arrays, names, axes)
4312 return mgr
4313 except ValueError as e:
-> 4314 construction_error(len(arrays), arrays[0].shape, axes, e)
4315
4316

/Users/wilmat01/anaconda/lib/python3.6/site-packages/pandas/core/internals.py in construction_error(tot_items, block_shape, axes, e)
4278 raise ValueError("Empty data passed with indices specified.")
4279 raise ValueError("Shape of passed values is {0}, indices imply {1}".format(
-> 4280 passed, implied))
4281
4282

ValueError: Shape of passed values is (4, 2), indices imply (4, 4)

Problem description

I see the same problem when fun returns a list (e.g. [1,2]) rather than tuple.

The error does not occur when apply is called with axis=0.

The error does not occur when I replace the Timestamp column with a column of integers.

Expected Output

A pandas Series containing tuples:

0 (1, 2)
1 (1, 2)
2 (1, 2)
3 (1, 2)
dtype: object

Output of pd.show_versions()

[paste the output of pd.show_versions() here below this line]

INSTALLED VERSIONS

commit: None

python: 3.6.1.final.0

python-bits: 64

OS: Darwin

OS-release: 16.7.0

machine: x86_64

processor: i386

byteorder: little

LC_ALL: None

LANG: en_GB.UTF-8

LOCALE: en_GB.UTF-8

pandas: 0.20.3

pytest: 3.0.7

pip: 9.0.1

setuptools: 27.2.0

Cython: 0.25.2

numpy: 1.13.3

scipy: 0.19.0

xarray: None

IPython: 5.3.0

sphinx: 1.5.6

patsy: 0.4.1

dateutil: 2.6.1

pytz: 2017.2

blosc: None

bottleneck: 1.2.1

tables: 3.3.0

numexpr: 2.6.2

feather: 0.4.0

matplotlib: 2.0.2

openpyxl: 2.4.7

xlrd: 1.0.0

xlwt: 1.2.0

xlsxwriter: 0.9.6

lxml: 3.7.3

bs4: 4.6.0

html5lib: 0.9999999

sqlalchemy: 1.1.9

pymysql: None

psycopg2: None

jinja2: 2.9.6

s3fs: None

pandas_gbq: None

pandas_datareader: None

Issue 2:
Hello guys, I'm using the apply method with axis=1 argument and returning a list for each row. The weird thing is when the length of this list is equal to the number of features in the original dataframe, this apply returns another dataframe, and a series if anything else. I don't know if this is intended, but it was very unexpected.

import numpy as np
import pandas as pd

df = pd.DataFrame(np.random.randn(6, 3), columns=['A', 'B', 'C'])

ans1 = df.apply(lambda x: [1, 2, 3], axis=1)
ans2 = df.apply(lambda x: [1, 2], axis=1)

assert type(ans1) is pd.DataFrame
assert type(ans2) is pd.Series