ValueError when applying a function that returns a list or tuple to a DataFrame that contains a Timestamp #17892
Description
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
funreturns 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