如何打印字符串的最后一次出现以及以下N行

Question

I'm trying to write a file output parser and am having trouble with coming up with a solution to how to print the last occurrence of a string + the following N number of lines. The output files are generally less than 2 MB so I shouldn't have any issues reading the file to memory, but if there is a more elegant solution that would be nice for learning sake.

I have tried saving the lines into a list and then printing out the last occurrences, but it splits the lines into words so the lists end up being to hard to work with. I also have the program reading the total number of lines needed to be printed earlier if there is another solution than what I have tried.

def coord():
    stdOrn = 'Standard orientation'
    coord = {}
    found = False
    with open(name, 'r') as text_file:
        for line in text_file:
            if stdOrn in line:
                found = True
            elif 'Rotational constants (GHZ)' in line:
                found = False
            elif found:
                coord = line

    outFile.write(coord)

Answer 1

You can load it as a string, get the index of the last appearance with .rfind() and then do a string slice from the last index.

stdOrn = 'Standard orientation'
found = False
with open(name, 'r') as text_file:
    file_contents = text_file.read()
    last_appearance = file_contents.rfind(std0rn)
    following_n_lines = file_contents[last_appearance:]