python - 有什么简单的方法可以用什么替换逗号吗？

Question

我正在尝试将字符串列表转换为 float ，但这不能用像 1,234.56 这样的数字来完成。有没有办法使用 string.replace() 函数删除逗号，所以我只有 1234.56？string.replace(',','') 似乎不起作用。这是我当前的代码:

fileName = (input("Enter the name of a file to count: "))
print()

infile = open(fileName, "r")
line = infile.read()
split = line.split()
for word in split:
    if word >= ".0":
        if word <= "9":
            add = (word.split())
            for num in add:
                  x = float(num)
                  print(x)

这是我得到的错误:

File "countFile.py", line 29, in main x = float(num) ValueError: could not convert string to float: '3,236.789'

Answer 1

在一个字符串上你可以替换任何字符，比如,，像这样:

s = "Hi, I'm a string"
s_new = s.replace(",", "")

---

此外，您对字符串所做的比较可能并不总是按照您期望的方式执行。最好先转换为数值。像这样的东西:

for word in split:
    n = float(word.replace(",", ""))
    # do comparison on n, like
    # if n >= 0: ...

---

作为提示，尝试使用 with 读取文件:

# ...
with open(fileName, 'r') as f:
    for line in f:
        # this will give you `line` as a string 
        # ending in '\n' (if it there is an endline)
        string_wo_commas = line.replace(",", "")
        # Do more stuff to the string, like cast to float and comparisons...

这是一种更惯用的方式来读取文件并对每一行做一些事情。