How to slice a list into sublists with different length

user_16949520 0
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Context: I want to make multiple word search grid

I have an Input of lines of text (containing string of numbers and letters) like this:

2           <--- tells how many grids/boxes 
3           <--- tells rows/length
4           <--- tells columns/width 
catt        <--\
aata        <--- letters that will fill the box
tatc        <--/
cat         <--- the word that will be search inside the box
5           <--- and repeat but start with the rows
5
gogog
ooooo
godog
ooooo
gogog
dog

all of that comes in one list as an input

However, I need to pass variables inside. so I assume that I need to split/slice the list into another lists containing all variables that I need.

I think I need to split the variables for cat and dog like this:

#variables for cat and dog
rows, cols = [3, 5], [4, 5] #the numbers have to be integer
matrix = [['catt', 'aata', 'tatc'], ['gogog', 'ooooo', 'godog', 'ooooo', 'gogog']]
word = ['cat', 'dog']

those are the variables I need. but I don't know how to split it like that from the input above.

If there are any different ways, feel free to explain. Thank you

list sorting python
3 Answers

I have saved your input in a file called "input.txt" and used the following approach:

with open("input.txt", "r") as f:
    lines = [x.strip() for x in f.readlines()]

n_animals, other_lines = int(lines[0]), lines[1:]

rows, cols, matrix, word = [[] for _ in range(4)] # comment by @Stef - well spotted

while len(other_lines) > 0:
    rows.append(int(other_lines[0]))
    cols.append(int(other_lines[1]))
    matrix.append(list(map(lambda x: x[:cols[-1]], other_lines[2:2 + rows[-1]])))
    word.append(other_lines[2 + rows[-1]])
    other_lines = other_lines[2 + rows[-1] + 1:]
    if len(matrix) == n_animals:
        pass # Do we need to take any action here? like break?

print(rows)
print(cols)
print(matrix)
print(word)

OUTPUT

[3, 5]
[4, 5]
[['catt', 'aata', 'tatc'], ['gogog', 'ooooo', 'godog', 'ooooo', 'gogog']]
['cat', 'dog']

My assumption was that you want to do something with that width variable, hence I have cut every word to cols[-1] characters. Now, you need to decide what to do if len(matrix) > n_animals.

FOLLOW UP

Incorporating some feedback for efficiency:

i = 0
while i < len(other_lines):
    rows.append(int(other_lines[i]))
    cols.append(int(other_lines[i + 1]))
    matrix.append(list(map(lambda x: x[:cols[-1]], other_lines[i + 2 : i + 2 + rows[-1]])))
    word.append(other_lines[i + 2 + rows[-1]])
    i += 2 + rows[-1] + 1
    if len(matrix) == n_animals:
        pass # Do we need to take any action here? like break?
user_76942630

If the position of the information in each line is always 'fixed', then the easiest option is to convert the lines to a list, and then reference each line specifically. Something like:

data = text.splitlines()
grids = data[0]
rows = data[1]
cols = data[2]
letters = data[3:7]
repeat = data[7:9]
remain = data[9:]

print(grids, rows, cols, letters, repeat, remain)
user_92031100

Using next to iterate through a file object:

with open('input.txt') as f:
    n_animal = int(next(f).strip())
    rows, cols, matrices, words = [], [], [], []
    for _ in range(n_animals):
        n_row = int(next(f).strip())
        n_col = int(next(f).strip())
        rows.append(n_row)
        cols.append(n_col)
        matrix = [list(next(f).strip()) for _ in range(n_row)]
        matrices.append(matrix)
        words.append(next(f).strip())

print('rows, cols = ', rows, cols)
print('matrices = ', matrices)
print('words = ', words)

# rows, cols =  [3, 5] [4, 5]
# matrices =  [[['c', 'a', 't', 't'], ['a', 'a', 't', 'a'], ['t', 'a', 't', 'c']], [['g', 'o', 'g', 'o', 'g'], ['o', 'o', 'o', 'o', 'o'], ['g', 'o', 'd', 'o', 'g'], ['o', 'o', 'o', 'o', 'o'], ['g', 'o', 'g', 'o', 'g']]]
# words =  ['cat', 'dog']

Note: if a list of strings is okay instead of a list of lists, then you can replace the matrix = line:

# list of lists
matrix = [list(next(f).strip()) for _ in range(n_row)]

# list of strings
matrix = [next(f).strip() for _ in range(n_row)]

If your input is already stored as a list of strings, rather than as a file to read from, you can still use next on an iterator:

lines = ['2', '3', '4', 'catt', ...]

f = iter(lines)

n_animal = int(next(f).strip())
rows, cols, matrices, words = [], [], [], []
for _ in range(n_animals):
    n_row = int(next(f).strip())
    n_col = int(next(f).strip())
    rows.append(n_row)
    cols.append(n_col)
    matrix = [list(next(f).strip()) for _ in range(n_row)]
    matrices.append(matrix)
    words.append(next(f).strip())
user_30807230
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