concat(axis=1) currently is not supported

Concatenating along the columns is a common use case but currently isn’t supported in koalas. We can achieve this by joining the dataframes by their index.

>>> df4 = pd.DataFrame([['bird', 'polly'], ['monkey', 'george']],
...                    columns=['animal', 'name'])
>>> pd.concat([df1, df4], axis=1)
  letter  number  animal    name
0      a       1    bird   polly
1      b       2  monkey  george

[HyukjinKwon]

I think this can be done with join(index_column) Are you interested in submitting a PR?

[HyukjinKwon]

You can work around as below:

>>> import databricks.koalas as ks
>>> df1 = ks.DataFrame([['bird', 'polly'], ['monkey', 'george']],
...                    columns=['animal', 'name'])
>>> df2 = ks.DataFrame([[1, 2], [3, 4]],
...                    columns=['num', 'int'])
>>> ks.set_option('compute.ops_on_diff_frames', True)
>>> df1['num'] = df2.num
>>> df1['int'] = df2.int
>>> df1
   animal    name  num  int
0    bird   polly    1    2
1  monkey  george    3    4

In fact, are you interested in creating a PR like the above? cc @itholic, @charlesdong1991, @harupy