如何按特定顺序组合文本文件中的行？

Question

我正在尝试根据以下规则转换文件中的文本：对于每一行，如果该行不是以“https”开头，则将该单词添加到后续行的开头，直到您用非 https 命中另一行单词。

例如，给定此文件：

Fruit
https://www.apple.com//
https://www.banana.com//
Vegetable
https://www.cucumber.com//
https://www.lettuce.com//

我想

Fruit-https://www.apple.com//
Fruit-https://www.banana.com//
Vegetable-https://www.cucumber.com//
Vegetable-https://www.lettuce.com//

这是我的尝试：

one = open("links.txt", "r")
for two in one.readlines():

    if "https" not in two:
        sitex = two
        
    else:
        print (sitex + "-" +two)

这是该程序的 output，使用上面的示例输入文件：

Fruit
-https://www.apple.com//

Fruit
-https://www.banana.com//       

Vegetable
-https://www.cucumber.com//     

Vegetable
-https://www.lettuce.com//   

我的代码有什么问题？

Answer 1

为了解决这个问题，我们需要为 sitex 实现rstrip()方法，以删除字符串末尾的换行符。 （归功于BrokenBenchmark ）

其次，打印命令每次调用时默认换行，所以我们必须添加end=""参数来解决这个问题。

所以你的代码应该是这样的

one = open("links.txt", "r")
for two in one.readlines():
    if "https" not in two:
        sitex = two.rstrip()
    else:
        print (sitex + "-" +two,end="")
one.close()

完成后也请始终关闭文件。

Answer 2

文件中的行以"\n" （换行符）结尾。

您可以使用strip() （两端）或rstrip() / lstrip() （在一端删除）从字符串中删除空格（包括"\n" ）。

print()默认在其末尾添加一个"\n" ，您可以使用省略它

print("something", end=" ")
print("more)   # ==> 'something more' in one line

修复您的代码：

# use a context handler for better file handling
with open("data.txt","w") as f:
    f.write("""Fruit
https://www.apple.com//
https://www.banana.com//
Vegetable
https://www.cucumber.com//
https://www.lettuce.com//
""")


with open("data.txt") as f:
    what = ""
    # iterate file line by line instead of reading all at once
    for line in f:
        # remove whitespace from current line, including \n
        # front AND back - you could use rstring here as well
        line = line.strip() 
        # only do something for non-empty lines (your file does not
        # contain empty lines, but the last line may be empty
        if line:
            # easier to understand condition without negation
            if line.startswith("http"):
                # printing adds a \n at the end
                print(f"{what}-{line}") # line & what are stripped
            else:
                what = line

Output：

Fruit-https://www.apple.com//
Fruit-https://www.banana.com//
Vegetable-https://www.cucumber.com//
Vegetable-https://www.lettuce.com//

看：

• str.lstrip( [字符] )
• str.rstrip( [字符] )
• str.strip( [字符] )

[chars]是可选的——如果没有给出，空格将被删除。

Answer 3

如果它不包含'https' ，则需要从该行中删除尾随换行符：

sitex = two

应该

sitex = two.rstrip()

---

正如ShadowRanger指出的那样，您还需要为else块做类似的事情：

print (sitex + "-" +two)

应该

print (sitex + "-" + two.rstrip())