如何使用python从文件中的当前行写入前几行

Question

如何从文件中的当前行抓取/写入前几行？ 例如在下面的文本中：...

Line 0: DATE
Line 1:
Line 2:
Line 3:    
Line 4:    
Line 5:
Line 6:  Phase=WATER
Line 7:
Line 8:
Line 9:
Line 10:
Line 11:

...

我目前正在使用下面的脚本写出感兴趣的行和上一行，但想扩展它以抓取/写入“Phase =”上方的 5 行：

...

prevline=""
for line in infile:
    if 'DATE' in line:
        macfile.write(line)
    elif 'Line7' in line:
        macfile.write(prevline)
        macfile.write(line)
        macfile.write("}""\n")
    elif 'Line10' in line:
        macfile.write(prevline)
        macfile.write(line)
        macfile.write("}""\n")
    prevline=line

...

Answer 1

更快的方法是：

lines = infile.read()

macfile.write(lines.split("Phase=WATER")[0])