如何在 Python 中将列表划分为交替大小的块？

Question

I need to divide a string into chunks of unequal sizes, that is,if in a for loop i meets a certain condition then the chunk should be of specific length otherwise of different length. Basically I need to create a 2d array(list) where I know the number of rows but don't know the number of columns as the length of string is unknown. I tried various methods on googling. Here is one I tried on own.

    a = [1,2,3,4,5,6,7,8]
b = []
c=[]
def divide_chunks(l): 
      
    # looping till length l 
    for i in range(0, len(l)):
        j = 0
        if(i%2==0):
           while(j<4 and i<=len(l)):
               b.append(l.pop())
               i = i+1
        else:
              while(j<2 and i<=len(l)):
               b.append(l.pop())
               i = i+1
        c.append(b)    

The problem I am facing is that the numbers or lets say words in case of string are getting overlapped in each chunk. For example one of the output is

[[8, 7, 6, 5, 4, 3, 2], [8, 7, 6, 5, 4, 3, 2], [8, 7, 6, 5, 4, 3, 2], [8, 7, 6, 5, 4, 3, 2], [8, 7, 6, 5, 4, 3, 2], [8, 7, 6, 5, 4, 3, 2], [8, 7, 6, 5, 4, 3, 2], [8, 7, 6, 5, 4, 3, 2]]

So I want to achieve something like if string is markisgoodboy. Then for first row it will take "mark" second row "is" and third row "good" and fourth row "bo" and last row "y". Please take note that it is row wise. The length of rows will be supplied as an argument for every method call. How to solve it? Thanks:)

Answer 1

This should work for both, lists and strings that don't contain empty elements:

def chunks(s, m, n):
    s1 = [s[i:i+m] for i in range(0, len(s), m+n)] 
    s2 = [s[i+m:i+m+n] for i in range(0, len(s), m+n)] 
    return [e for t in zip(s1, s2) for e in t if e]

s = '1234567890ABCDEFGHIJKLMNO'
m = 4
n = 2

print(chunks(list(s), m, n))
print(chunks(s, m, n))

Sample output:

[['1', '2', '3', '4'], ['5', '6'], ['7', '8', '9', '0'], ['A', 'B'], ['C', 'D', 'E', 'F'], ['G', 'H'], ['I', 'J', 'K', 'L'], ['M', 'N'], ['O']]
['1234', '56', '7890', 'AB', 'CDEF', 'GH', 'IJKL', 'MN', 'O']