如何将txt文件中的元组添加到没有引号的列表中？ 蟒蛇

Question

Ok, so I have a txt file of tuples like such:

("Item1", 2, 3, 4)
("Item2", 3, 4, 5)
("Item3", 4, 5, 6)

Each tuple will be set on its own line and exactly like that where item 0 is a string and the other 3 are numbers. Now for the part I am having trouble with. Basically, I want to read the tuple and add it to a list. Here is what I came up with:

with open('data.txt', 'r', encoding='utf-8') as file:
     lst = [line.strip() for line in file]

It adds each item to the list. However, each item is converted to a string in the process. How would I get just the tuple value.

Answer 1

You can use ast.literal_eval() :

import ast
with open('data.txt', 'r', encoding='utf-8') as file:
    lst = [ast.literal_eval(line.strip()) for line in file]

This safely evaluates the string to a tuple. It is safer than using eval() .

---

You may also want to consider using the pickle module for writing and reading such data. Here's an example:

import pickle
with open('a.txt', 'w') as myfile:
    pickle.dump([("Item1", 2, 3, 4), ("Item2", 3, 4, 5), ("Item3", 4, 5, 6)], myfile)

with open('a.txt', 'rb') as myfile2: # Open in bytes
    lst = pickle.load(myfile2)
    for tup2 in lst:
        print tup2

Answer 2

Use regex?

def main():
    filename = sys.argv[1]
    fp = open(filename, 'r') # TODO error handling
    text = fp.read()
    fp.close()

    matches = re.findall(r'\(\"([^"]+)\",\s+(\d+),\s+(\d+),\s+(\d+)\)', text)
    for match in matches:
        (itemname, num1, num2, num3) = match
        print itemname, num1, num2, num3
        # Do whatever you want with them