如何从文件中读取特定行(按行号)? [英] How to read specific lines from a file (by line number)?

问题描述

我正在使用 for 循环读取文件，但是我只想读取特定的行，例如#26 和#30 .有内置的功能可以实现这一点吗?

I'm using a for loop to read a file, but I only want to read specific lines, say line #26 and #30. Is there any built-in feature to achieve this?

推荐答案

如果要读取的文件很大，并且您不想一次读取内存中的整个文件:

If the file to read is big, and you don't want to read the whole file in memory at once:

fp = open("file")
for i, line in enumerate(fp):
    if i == 25:
        # 26th line
    elif i == 29:
        # 30th line
    elif i > 29:
        break
fp.close()

请注意，第 n 行的 i == n-1 .

在Python 2.6或更高版本中:

In Python 2.6 or later:

with open("file") as fp:
    for i, line in enumerate(fp):
        if i == 25:
            # 26th line
        elif i == 29:
            # 30th line
        elif i > 29:
            break

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