Python 切片输出文件

我正在读取一个大文件，我想将其中的某一部分写入一个新文件

模式“笛卡尔坐标”在这个文件中出现了两次，我想在新文件中第二次出现之前省略所有内容。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() 

---

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

如果我没弄错的话，你想要第二个笛卡尔坐标之后的所有东西：

#!/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)

这些导入都不是工作所必需的，我只是把它们放在那里，因为它们在您的原始代码片段中

这将输出到

101.xyz

：

written
written
written