jezrael - 1 year ago 145
Python Question

# Python: Merge list with range list

I have a

`list`
:

``````L = ['a', 'b']
``````

I need to create a new
`list`
by concatenating an original
`list`
which range goes from
`1`
to
`k`
. Example:

``````k = 4
L1 = ['a1','b1', 'a2','b2','a3','b3','a4','b4']
``````

I try:

``````l1 = L * k
print l1
#['a', 'b', 'a', 'b', 'a', 'b', 'a', 'b']

l = [ [x] * 2  for x in range(1, k + 1) ]
print l
#[[1, 1], [2, 2], [3, 3], [4, 4]]

l2 = [item for sublist in l for item in sublist]
print l2
#[1, 1, 2, 2, 3, 3, 4, 4]

print zip(l1,l2)
#[('a', 1), ('b', 1), ('a', 2), ('b', 2), ('a', 3), ('b', 3), ('a', 4), ('b', 4)]

print [x+ str(y) for x,y in zip(l1,l2)]
#['a1', 'b1', 'a2', 'b2', 'a3', 'b3', 'a4', 'b4']
``````

But I think it is very complicated.
What is the fastest and most generic solution?

You can use a list comprehension:

``````L = ['a', 'b']
k = 4
L1 = ['{}{}'.format(x, y) for y in range(1, k+1) for x in L]
print(L1)
``````

Output

``````['a1', 'b1', 'a2', 'b2', 'a3', 'b3', 'a4', 'b4']
``````
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