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How would you "columnize" a list of lists at every xth index?

I was thinking of doing this by taking the starting list, then creating two new lists, merging them, then adding the remainder not divisible by x.

For example with an interval of 2:

start = [
 [1, 'one'],
 [2, 'two'],
 [3, 'three'],
 [4, 'four'],
 [5, 'five'],
 [6, 'six'],
 [7, 'seven'],
 [8, 'eight'],
 [9, 'nine'],
]
expected = [
 [1, 'one', 3, 'three'],
 [2, 'two', 4, 'four'],
 # page break
 [5, 'five', 7, 'seven'],
 [6, 'six', 8, 'eight'],
 # page break
 [9, 'nine'],
]

Just wondering if there's a quick way of doing this?

I agree with the comments about this being a strange way to 'collumize'. However, here is a function that does what you described:

def columnize(A, interval=2):
 ans = 
 for i in range(0,len(A), interval*2):
 for j in range(min(interval, len(A)-i)):
 ans.append(A[i+j] + (A[i+j+interval] if i+j+interval < len(A) else ))
 return ans

Are you looking for something like this? Columnizing squared matrix?

start = [
 [1, 'one'],
 [2, 'two'],
 [3, 'three'],
 [4, 'four'],
 [5, 'five'],
 [6, 'six'],
 [7, 'seven'],
 [8, 'eight'],
 [9, 'nine'],
]
expected = [
 [1, 'one', 3, 'three'],
 [2, 'two', 4, 'four'],
 # page break
 [5, 'five', 7, 'seven'],
 [6, 'six', 8, 'eight'],
 # page break
 [9, 'nine'],
]
a = 2
r = a*a
ans = 
for i in range(0, len(start), r):
 l_tmp = start[i:i+r]
 if l_tmp[::a]:
 ans.append([item for sublist in l_tmp[::a] for item in sublist])
 if l_tmp[1::a]:
 ans.append([item for sublist in l_tmp[1::a] for item in sublist])
 # You can easily add page break here
print(ans)