如何将 Python 文件中的字符串数字转换为整数？

Question

# writeFile() method is used to open the same file in write mode.
# This is used in order to over write the file.
# Then it traverses through the dictionary and writes all items to the file.
def writeFile():
    file = open("Stocks.txt","w")        
    for stock in stocks:
        file.write(stock+" "+str(stocks[stock])+"\n")
    file.close()

# Program starts here.
# We open the file "Stocks.txt" in read mode.
file = open("Stocks.txt","r")
# Instead of using lists we can store the data in the dictionary.
# We have initialized a dictionary named stocks.
stocks = {}
# Now we traverse through the file line by line.
for line in file:
    # The line must be in the format of Apple 10
    # So we split this line into 2 parts the name and the quantity.
    # split() returns the splitted words as an list.
    # The first part gives name and second part gives quantity.
    #  We type cast the second part into integer data type.
    name = line.split(" ")[0]
    qty = int(line.split(" ")[1])
    # If the name already exists in the dictionary then we add the quantity to the existing quantity.
    if name in stocks.keys():
        stocks[name]+=qty
        # And we call the writeFile() function
        writeFile()
    # If the name doesn't exist then we add it to the dictionary.
    else:
        stocks[name] = qty

# After reading the file we prompt the user if they want to add any other items.
while True:
    cont = input("Do you want to add stocks ? (Y/N)")
    # If user enters N which means no then it exists the loop.
    if(cont=='N'):
        break
    # else asks the user name of the item and the quantity.
    else:
        name = input("Enter the item name: ")
        qty = int(input("Enter the quantity: "))
        # If it already exists then we just add the quantity to the existing quantity.
        if name in stocks.keys():
            stocks[name]+=qty
        # else we add it to the dictionary.
        else:
            stocks[name] = qty
        # Then we call the writeFile method
        writeFile()

This program needs to open a file that contains a stock of items. This only works if the items are like this in the file "Apple 10", but they are like this in the file, "Key Lime Pie 20". So how do I get it so that I can change the string numbers into integers?

Answer 1

Rather than splitting the line on spaces, use regex to split the string on any character that is a number.

You can still use split, but do something like:

 re.split('\d', line)

Answer 2

you can remove all the symbols using regex

s = "how much for the maple syrup? $20.99? That's ridiculous!!!"
s = re.sub(r'[^\w]', ' ', s)
print(s)

>>>how much for the maple syrup   20 99  That s ridiculous  '

split using space then check if it's digit number using str.isdigit() function

def getint(x):
    return x.isdigit()

a = [i for i in s.split(' ') if getint(i)]
print(a)
>>> ['20', '99']

if you are pretty sure there will only be one integer on a sentence, just call int(a[0])

if you need all those numbers, just iterate

you still can improve this answer