Python从文件

Question

删除“一对多”行，我试图从一个文件的方式，如

./foo.py FILENAME.TXT 4 5 2919

删除蟒蛇具体的行号其中4 5和2919是行号

我所试图做的是：

for i in range(len(sys.argv)): 
    if i>1: # Avoiding sys.argv[0,1] 
     newlist.append(int(sys.argv[i])) 

然后：

count=0 

generic_loop{ 
    bar=file.readline() 
    count+=1 
    if not count in newlist: 
     print bar 
} 

它打印在原始文件中的所有行（之间的空格）

Answer 1

你可以尝试这样的事情：

import sys 
import os 
filename= sys.argv[1] 
lines = [int(x) for x in sys.argv[2:]] 

#open two files one for reading and one for writing 

with open(filename) as f,open("newfile","w") as f2: 

#use enumerate to get the line as well as line number, use enumerate(f,1) to start index from 1 
    for i,line in enumerate(f): 
     if i not in lines:  #`if i not in lines` is more clear than `if not i in line` 
      f2.write(line) 
os.rename("newfile",filename) #rename the newfile to original one  

注意，对于临时文件的生成，最好使用tempfile模块。

Answer 2

您可以使用enumerate来确定行号：

import sys 
exclude = set(map(int, sys.argv[2:])) 
with open(sys.argv[1]) as f: 
    for num,line in enumerate(f, start=1): 
     if num not in exclude: 
      sys.stdout.write(line) 

您可以删除start=1，如果你开始计数为0.在上面的代码中，行编号以1开头：

$ python3 so-linenumber.py so-linenumber.py 2 4 5 
import sys 
with open(sys.argv[1], 'r') as f: 
      sys.stdout.write(line) 

如果要将内容写入文件本身，请将其写入temporary file而不是sys.stdout，然后将rename即写入原始文件名（或在命令行上使用sponge），如下所示：

import os 
import sys 
from tempfile import NamedTemporaryFile 
exclude = set(map(int, sys.argv[2:])) 
with NamedTemporaryFile('w', delete=False) as outf: 
    with open(sys.argv[1]) as inf: 
     outf.writelines(line for n,line in enumerate(inf, 1) if n not in exclude) 
    os.rename(outf.name, sys.argv[1]) 

Answer 3

import sys 
# assumes line numbering starts with 1 
# enumerate() starts with zero, so we subtract 1 from each line argument 
omitlines = set(int(arg)-1 for arg in sys.argv[2:] if int(arg) > 0) 
with open(sys.argv[1]) as fp: 
    filteredlines = (line for n,line in enumerate(fp) if n not in omitlines) 
    sys.stdout.writelines(filteredlines) 

Answer 4

的fileinput模块有一个inplace=True选项，标准输出重定向到该系统会自动为你改名后一个临时文件。

import fileinput 
exclude = set(map(int, sys.argv[2:])) 

for i, line in enumerate(fileinput.input('filename.txt', inplace=True), start=1): 
    if i not in exclude: 
     print line, # fileinput inplace=True redirects stdout to tempfile