How do I converted the string of a nested list back to a nested list?

Question

Sorry if this is breaking any rules, it's my first time posting here. The project that we're working on is to create Connect 4 in Python. We're currently struggling on how to get the game to save and load.

What we're doing so far is saving our 2D list in a .txt file and trying to load the game by reading it. The problem that we've encountered is when you're trying to read the file, it reads as a string instead of a list. For example:

[['R', 'R', 'Y', 'R', 'Y', 'Y', 'Y'], ['Y', 'Y', 'R', 'R', 'R', 'Y', 'Y'], ['R', 'R', 'E', 'E', 'E', 'E', 'E'], ['E', 'E', 'E', 'E', 'E', 'E', 'E'], ['E', 'E', 'E', 'E', 'E', 'E', 'E'], ['E', 'E', 'E', 'E', 'E', 'E', 'E']]

That gets saved as a string and we'd like to convert it back to be used to place saved dots back where they belong.

def save():
    global GAME_LIST
    save_file = open("savedGame.txt","w")
    print('Game', GAME_LIST)
    save_file.write(str(GAME_LIST))


#Will basically be the new def main() once you load a file.
def load():
    global PIECES
    savedFile = open("savedGame.txt","r")
    loadedState = savedFile.readline()
    print(loadedState)
    grid()
    PIECES = {'1': 0, '2': 0, '3': 0, '4': 0, '5': 0, '6': 0, '7': 0}

def newRed(column):
    coordinates = {'1': -210, '2': -140, '3': -70, '4': 0, '5': 70,        '6': 140, '7': 210}
    red = turtle.Turtle()
    red.hideturtle()
    red.up()
    #Pieces * Cell length for Y value
    red.goto(coordinates[column], -160 + (PIECES[column] * 70))
    PIECES[column] += 1
    red.dot(60, 'red')

def newYellow(column):
    coordinates = {'1': -210, '2': -140, '3': -70, '4': 0, '5': 70, '6': 140, '7': 210}
    #Computer turtle
    yellow = turtle.Turtle()
    yellow.hideturtle()
    yellow.up()
    yellow.goto(coordinates[column], -160 + (PIECES[column] * 70))
    PIECES[column] += 1
    yellow.dot(60, 'yellow')

def toList(stringState):
    sublist = []
    for characters in stringState:
        sublist.append(characters)
    print(sublist)
    return sublist

def reDot(loadedState):
    global ROW
    global COLUMN
    for sortList in range(ROW):
        newList = loadedState[sortList]
        for sortSubList in range(COLUMN):
            sortSubList = int(sortSubList)
            if newList[sortSubList] == "R":
                newRed(sortSubList + 1)
            elif newList[sortSubList] == "Y":
                newYellow(sortSubList + 1)

newList = toList(loadedState)
reDot(newList)

This is a snippet of our code for reference. reDot() is supposed to take the location of 'R'/'Y' and place a dot there.

`ast.literal_eval("[['R', 'R', 'Y', 'R', 'Y', 'Y', 'Y'], ['Y', 'Y', 'R', 'R', 'R', 'Y', 'Y'], ['R', 'R', 'E', 'E', 'E', 'E', 'E'], ['E', 'E\ ', 'E', 'E', 'E', 'E', 'E'], ['E', 'E', 'E', 'E', 'E', 'E', 'E'], ['E', 'E', 'E', 'E', 'E', 'E', 'E']]")` — Akshay Hazari, Nov 25 '15 at 05:31
Possible duplicate of [convert string representation of list to list in python](http://stackoverflow.com/questions/1894269/convert-string-representation-of-list-to-list-in-python) — Akshay Hazari, Nov 25 '15 at 05:32
May be better to use JSON format...serialize and de-serialize.. — Iron Fist, Nov 25 '15 at 05:41

score 1 · Answer 1 · answered Nov 25 '15 at 05:57

If you want to save data into files and read them back, I think JSON library will be helpful to you, very easy to use, this way:

data = [['R', 'R', 'Y', 'R', 'Y', 'Y', 'Y'], ['Y', 'Y', 'R', 'R', 'R', 'Y', 'Y'], ['R', 'R', 'E', 'E', 'E', 'E', 'E'], ['E', 'E', 'E', 'E', 'E', 'E', 'E'], ['E', 'E', 'E', 'E', 'E', 'E', 'E'], ['E', 'E', 'E', 'E', 'E', 'E', 'E']]
with open('game_data.json', 'w') as fp:
                    json.dump(data, fp)

And then when you want to read it back:

with open('game_data.json', 'r') as fp:
                data = fp.read()

You may also want to wrap the above code with a try-except block in case the file was not found or any other exception.

How do I converted the string of a nested list back to a nested list?

1 Answers1