Python-сообщество

>>> a[:,[2,3]]
array([[ 0.,  0.],
       [ 0.,  0.],
       [ 0.,  0.],
       [ 0.,  0.],
       [ 0.,  0.]])

>>> text = """\
... a1\tb1\tc1\td1
... a2\tb2\tc2\td2
... a3\tb3\tc3\td3
... a4\tb4\tc4\td4
... """
>>> 
>>> def f(lines):
...     out = []
...     for i in lines:
...         parts = i.split('\t')
...         c1, c3 = parts[0], parts[2]
...         out.append([c1, c3])
...     return out
... 
>>> print(text)
a1      b1      c1      d1
a2      b2      c2      d2
a3      b3      c3      d3
a4      b4      c4      d4
 
>>> f(text.splitlines())
[['a1', 'c1'], ['a2', 'c2'], ['a3', 'c3'], ['a4', 'c4']]
>>>