Replace a specific word given its position in a text file (Python)

Question

I have a list of tuples, each on contains a word-to-be-replaced, its line and column number positions from a given text file. I want to go through the text file and repl

Answer 1

Consider a single line:

word1 a word2 a word3 a word4

If you have these changes:

[('word1', 1, 1), ('word2', 1, 9), ... ]

And you process them in order:

* a word2 a word3 a word4

You will fail, because you are changing the positions of the words when you replace 'word1' with '*', a shorter string.

Instead, you will have to sort the list of changes by line, reversed by column:

changes = sorted(changes, key=lambda t: (t[1], -t[2]))

You can then process the changes as you iterate through the file, shown in the link referenced by @JRajan:

with open("file", "r") as fp:
    fpline_text = enumerate(fp)
    fpline,text = next(fpline_text)

    for edit in changes:
        word,line,offset = edit
        line -=1  # 0 based

        while fpline < line:
            print(text)
            fpline,text = next(fpline_text)

        offset -= 1    # 0-based
        cand = text[offset:offset+len(word)]

        if cand != word:
            print("OOPS! Word '{}' not found at ({}, {})".format(*edit))
        else:
            text = text[0:offset]+'*'+text[offset+len(word):]

    # Rest of file
    try:
        while True:
            print(text)
            fpline,text = next(fpline_text)
    except StopIteration:
        pass