Extract specific text lines?

Question

I have a large several hudred thousand lines text file. I have to extract 30,000 specific lines that are all in the text file in random spots. This is the program I have to extr

Answer 1

If the line begins with S0414, then you could use the .startswith method:

if line.startswith('S0414'): small_file3.write(line)

You could also strip left whitespace, if there is any:

line.lstrip().startswith('S0414')

If 'S0414' always appears after a certain point, for example, it is always at least 10 characters in and never in the last 5 characters, you could do:

'S0414' in line[10:-5]

Otherwise, you will have to search through each line, like you are.