Question

我是Python的新手。我有一个源文件，其中有10行。使用Python我想将1个特定行导入新文件。

请告诉我如何处理此事。

Answer 1

如果您知道之后的行数，可以使用linecache：

import linecache
a_line = linecache.getline('/tmp/file.txt', 4)

# save it to new file
with open('new_file.txt', 'w') as f:
          f.write(a_line)

Answer 2

你可以写一个“for”循环来逐行计数，直到你想要的那一行。之后，将该行的副本保存到变量中，在本例中为“stringTemp”：

with open("file.txt", "r") as inputStream: # open a file.txt onto a stream variable
stringTemp = ""  # initialize an empty string, where you'll save the line you want
particularLineNumber = 3
count = 0      # a variable to keep count of which line you are on
for line in inputStream:   # "for each thing in the stream variable, save it onto "line"
    if count == particularLineNumber - 1: # if we are on the line we want...
        stringTemp = line                 # ... save it to stringTemp
    count = count + 1         # if we are NOT on the line we want, increase the counter


# ... write the variable stringTemp onto another file ...

我假设您希望您的行号为“1,2,3,4，...，9,10”。如果您决定从0开始（“0,1,2,3 ... 10”），则删除“if count == specialLineNumber - 1”上的“ - 1”

Answer 3

这将立即读取整个文件：

with open(fname) as f:
    content = f.readlines()

读完所有行后，你可以用它做任何你想做的事。

这将一次读取一行文件：

with open(fname) as f:
    for line in f:
        <do something with line>

但这已被多次回答：

How to read large file, line by line in python

How do I read a file line-by-line into a list?

从文本文件导入Python中的特定行

3 个答案: