You pass a string as the second argument. In effect, you're trying to do something like:
df.'two'
Which is invalid syntax. If you're trying to dynamically access a column, you'll need to use the index notation, [...]
because the dot/attribute accessor notation doesn't work for dynamic access.
Dynamic access on its own is possible. For example, you can use getattr
(but I don't recommend this, it's an antipattern):
In [674]: df
Out[674]:
one two
0 1 1
1 2 0
2 3 0
In [675]: getattr(df, 'one')
Out[675]:
0 1
1 2
2 3
Name: one, dtype: int64
Dynamically selecting by attribute from a groupby call can be done, something like:
In [677]: getattr(df.groupby('one'), mycol).sum()
Out[677]:
one
1 1
2 0
3 0
Name: two, dtype: int64
But don't do it. It is a horrid anti pattern, and much more unreadable than df.groupby('one')[mycol].sum()
.
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