调用函数中的子函数来处理Python中的同一个文件？

Question

我还在用python复制并替换行，问题Here。基本上，我想统计某个部分中某个模式的数量，然后在行中进行更新。我想我已经在我的问题中发现了这个问题：我调用一个子函数来在主函数中使用同一个文件，并且这个函数在时间上变得混乱起来。我对编程非常陌生，我不知道如何以另一种方式做这个copy-statistics-replace-copy事情。任何建议或提示是值得欢迎的。

下面是部分代码是我现在得到：

# sum number of keyframes 
def sumKeys (sceneObj, objName): 
    sceneObj.seek(0) 
    block = [] 
    Keys = "" 
    for line in sceneObj: 
     if line.find("ObjectAlias " + objName + "\n") != -1: 
      for line in sceneObj: 
       if line.find("BeginKeyframe") != -1: 
        for line in sceneObj: 
         if line.find("default") != -1: 
          block.append(line.rstrip()) 
          Keys = len(block) 
         elif line.find("EndKeyframe") != -1: 
          break 
        break 
      break 
    return (Keys) 

# renew number of keyframes 
def renewKeys (sceneObj, objName): 
    sceneObj.seek(0) 
    newscene = "" 
    item = [] 
    for line in sceneObj: 
     newscene += line 
     for obj in objName: 
      if line.find("ObjectAlias " + obj + "\n") != -1: 
       for line in sceneObj: 
        if line.find("EndKeyframe") != -1: 
         newscene += line 
         break 
        if line.find("BeginKeyframe") != -1: 
         item = line.split() 
         newscene += item[0] + " " + str(sumKey(sceneObj, obj)) + " " + item[-1] + "\n" 
         continue 
        else: 
         newscene += line 
    return (newscene) 

原文：

lines 
BeginObjects 
lines 
ObjectAlias xxx 
lines 
BeginKeyframe 34 12 ----> 34 is what I want to replace 
lines 
EndObject 
BeginAnotherObjects 
... 

目标：

lines 
BeginObjects 
lines 
ObjectAlias xxx 
lines 
BeginKeyframe INT 12 ---->INT comes from sumKeys function 
lines 
EndObject 
BeginAnotherObjects 
... 

Answer 1

您可以使用tell和seek到一个文件中移动，所以要做你想做的事情，你可以使用这样的东西，我砍了醚：

import re 

# so, we're looking for the object 'HeyThere' 
objectname = 'HeyThere' 

with open('input.txt', 'r+') as f: 
    line = f.readline() 
    pos = f.tell() 
    found = False 
    while line: 

     # we only want to alter the part with the 
     # right ObjectAlias, so we use the 'found' flag 
     if 'ObjectAlias ' + objectname in line: 
      found = True 
     if 'EndObject' in line: 
      found = False 

     if found and 'BeginKeyframe' in line: 

      # we found the Keyframe part, so we read all lines 
      # until EndKeyframe and count each line with 'default' 
      sub_line = f.readline() 
      frames = 0 
      while not 'EndKeyframe' in sub_line: 
       if 'default' in sub_line: 
        frames += 1 
       sub_line = f.readline() 

      # since we want to override the 'BeginKeyframe', we 
      # have to move back in the file to before this line 
      f.seek(pos) 

      # now we read the rest of the file, but we skip the 
      # old 'BeginKeyframe' line we want to replace 
      f.readline() 
      rest = f.read() 

      # we jump back to the right position again 
      f.seek(pos) 

      # and we write our new 'BeginKeyframe' line 
      f.write(re.sub('\d+', str(frames), line, count=1)) 

      # and write the rest of the file 
      f.write(rest) 
      f.truncate() 
      # nothing to do here anymore, just quit the loop 
      break 

     # before reading a new line, we keep track 
     # of our current position in the file 
     pos = f.tell() 
     line = f.readline() 

这些评论几乎可以解释发生了什么。

鉴于像

foo 
bar 
BeginObject 
something 
something 
ObjectAlias NotMe 
lines 
more lines 
BeginKeyframe 22 12 
foo 
bar default 
foo default 
bar default 
EndKeyframe 
EndObject 
foo 
bar 
BeginObject 
something 
something 
ObjectAlias HeyThere 
lines 
more lines 
BeginKeyframe 43243 12 
foo 
bar default 
foo default 
bar default 
foo default 
bar default 
foo default 
bar 
EndKeyframe 
EndObject 

输入文件将取代线

BeginKeyframe 43243 12 

与

BeginKeyframe 6 12