A small, complete example of the issue
# Your code here
xx = pd.to_datetime(['2000-01-01','2000-02-01'])
xx.append(xx[0])
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "C:\Anaconda\lib\site-packages\pandas\tseries\index.py", line 1058, in append
return factory(to_concat)
File "C:\Anaconda\lib\site-packages\pandas\tseries\index.py", line 2240, in <lambda>
factory_func = lambda x: klass(concat(x), name=name, **kwargs)
ValueError: all the input arrays must have same number of dimensions
# insert works as expected
xx.insert(0, xx[0])
DatetimeIndex(['2000-01-01', '2000-01-01', '2000-02-01'], dtype='datetime64[ns]', freq=None)
Expected Output
append one item at the end of xx
Output of pd.show_versions()
INSTALLED VERSIONS
commit: None python: 2.7.12.final.0 python-bits: 64 OS: Windows OS-release: 7 machine: AMD64 processor: Intel64 Family 6 Model 44 Stepping 2, GenuineIntel byteorder: little LC_ALL: None LANG: en_GB
pandas: 0.18.1 nose: 1.3.7 pip: 8.1.0 setuptools: 0.6c11 Cython: 0.21 numpy: 1.10.1 scipy: 0.16.0 statsmodels: 0.6.1 xarray: None IPython: 5.1.0 sphinx: 1.3.1 patsy: 0.4.0 dateutil: 2.4.2 pytz: 2015.7 blosc: None bottleneck: None tables: 3.1.1 numexpr: 2.4.4 matplotlib: 1.4.3 openpyxl: 1.8.5 xlrd: 0.9.3 xlwt: 0.7.5 xlsxwriter: 0.5.7 lxml: 3.5.0 bs4: 4.4.1 html5lib: None httplib2: None apiclient: None sqlalchemy: 0.9.7 pymysql: None psycopg2: None jinja2: 2.8 boto: 2.32.1 pandas_datareader: None
Comment From: chris-b1
append expects another Index (or really an array-like), so to append a single element, you could, for instance, take a length 1 slice.
Note that in general, appending or inserting single elements to arrays is expensive (full copy each time), so often best to avoid if you can (e.g. use a python list to build up your values, then convert to an Index)
In [24]: xx.append(xx[0:1])
Out[24]: DatetimeIndex(['2000-01-01', '2000-02-01', '2000-01-01'], dtype='datetime64[ns]', freq=None)
In [25]: pd.DatetimeIndex.append?
Signature: pd.DatetimeIndex.append(self, other)
Docstring:
Append a collection of Index options together
Parameters
----------
other : Index or list/tuple of indices
Returns
-------
appended : Index
Type: function