替换文本文件（注释文件）中每一行的第一个单词（标签）-Python代码

Question

I am still beginner with the Python and need to modify labels of my annotations with.txt format. The.txt annotation format looks like below:

10 0.31015625 0.634375 0.0890625 0.2625
9 0.37109375 0.35703125 0.0671875 0.2015625

And I need to replace the first number (class number/label) as:

• 10-->7

• 9-->6

• 6-->5

• 11-->8

• 8-->5

  I have written the following code but still it is far behind a complete one and I am kinda stuck.

    replacements = {'6':'5', '9':'6', '10':'7', '11':'8', '8':'5'}
    
    with open('data.txt') as infile, open('out.txt', 'w') as outfile:
        for line in infile:
            word=line.split(" ",1)[0]
            for src, target in replacements.items():
                word = word.replace(src, target)
            outfile.write(line)

Answer 1

You don't have to loop through all of the replacements. You can just check if the first word is in your replacements dictionary. I'm assuming you only want to replace the first word.

word, tail = line.split(" ", 1)
if word in replacements:
  word = replacements[word]

outfile.write(word + " " + tail)

Your code doesn't change line , ie changing word does not change line as it is a different value. In general, strings are immutable in Python (but not lists), so you can't change a string object through a reference. Operations on strings will return new string objects.