Inability to change string-CodePudding

I am trying to solve a maze question.

maze = [
"#o######",
"# ##   #",
"# ## # #",
"#    # #",
"## ### #",
"##  ## #",
"######e#",
]

maze[0][1] = "#"

Output:

TypeError: 'str' object does not support item assignment

I thought of an algorithm that works with the logic of filling the space behind me with a "#" every time I move forward. But I learned that strings are immutable.

Is there anything in Python that allows me to run this algorithm in another way?

CodePudding user response：

You can only access specific char from string using its index, but you cannot change it. You have to recreate it, eg. to change first digit of string:

text = 'abcdef'
text = 'X'   text[1:] # changes first letter to X and adds rest of the string
> 'Xbcdef'

Or more general example:

def change(text, char, index):
    return text[:index]   char   text[(index 1):]

text = 'abcdef'
text = change(text, 'X', 2)
> 'abXdef'

So i your maze case:

maze = [
"#o######",
"# ##   #",
"# ## # #",
"#    # #",
"## ### #",
"##  ## #",
"######e#",
]

maze[0] = change(maze[0], '#', 1)

CodePudding user response：

You can change the list of strings to a list of lists by doing

maze = [list(s) for s in maze] #list comprehension

or more verbosely

for i in range(len(maze)):
    maze[i] = list(maze[i])

Then you can do things like maze[0][1] = "#".

If you want it back in string form, do

maze = ["".join(lst) for lst in maze]

for i in range(len(maze)):
    maze[i] = "".join(maze[i])

CodePudding user response：

You can use replace method instead.

maze = [
"#o######",
"# ##   #",
"# ## # #",
"#    # #",
"## ### #",
"##  ## #",
"######e#",
]
for i in maze:
    j = i.replace("o","#")
    print(j)