Question

I have a tab-delimited file as below:

A    3    A    6
B    6    B    9
C    0    C    2

I wish to read the file in as below:

LIST = [['A', '3'], ['B', '6'], ['C', '0'], ['A', '6'], ['B', '9'], ['C', '2']]

The order is not important. I am only concerned that each row is read in increments of two and assigned to a sub list.

Any suggestions?

Thanks,
S 🙂

Answer 1

The most straightforward way would be:

>>> n = []
>>> for line in open(fname):
    els = line.split('\t')
    n.append(els[:2])
    n.append(els[2:])


>>> n
[['A', '3'], ['A', '6'], ['B', '6'], ['B', '9'], ['C', '0'], ['C', '2']]

maybe slightly more efficient would be:

>>> g = (line.split('\t') for line in open(fname))
>>> [els[i:i+2] for els in g for i in range(0, 4, 2)]
[['A', '3'], ['A', '6'], ['B', '6'], ['B', '9'], ['C', '0'], ['C', '2']]