python - 切片输出文件

Question

我正在读取一个大文件，并且想将其中的一部分写入新文件。

模式“笛卡尔坐标”在此文件中出现两次，我想忽略新文件中第二次出现之前的所有内容。到目前为止我已经:

#!/usr/bin/env python
import string,sys
import numpy as np
from numpy import *

with open("101.out", "r") as f:
    content = []
    for line in f:
        content.append(line)

g = open('101.xyz', 'w')


#write the relevant stuff


f.close() 

Answer 1

所以我假设 101.out 文件看起来像:

not to be written 
not to be written
CARTESIAN COORDINATES
not to be written
CARTESIAN COORDINATES
written 
written
written

如果我理解正确的话，你想要第二个CARTESIAN COORDINATES之后的所有内容:

#!/usr/bin/env python
import string,sys
import numpy as np
from numpy import *

with open("101.out", "r") as f:
    content = []
    occurances = 0
    for line in f:
        if occurances >= 2: 
            content.append(line)
        if 'CARTESIAN COORDINATES' in line:
            occurances += 1

with open('101.xyz', 'w') as f:
    for item in content:
        f.write(item)

这项工作不需要这些导入，我只是将它们留在那里，因为它们位于您的原始片段中。

这输出到101.xyz:

written
written
written