根据其内容拆分文本文件 [英] Split up a text file based on its contents

问题描述

我有一个文本文件，如下所示:

I have a text file that looks like this:

SYSTEM

DOF=UY,UZ,RX  LENGTH=FT  FORCE=Kip

JOINT
  1  X=0  Y=-132.644  Z=0
  2  X=0  Y=-80  Z=0
  3  X=0  Y=-40  Z=0
  4  X=0  Y=0  Z=0
  5  X=0  Y=40  Z=0
  6  X=0  Y=80  Z=0
  7  X=0  Y=132.644  Z=0

等10,000个关节.

etc. for 10,000 joints.

我想编写一个脚本，该脚本读取此文本文件并输出4个文本文件，这些文件为1列，每个列包含关节编号，x坐标，y坐标和z坐标.

I would like to write a script that reads this text file and outputs 4 text files that are 1 column each containing the joint number, x coordinate, y coordinate, and z coordinate.

这可能吗?我是python的新手，并尝试过类似的方法，但是Python不知道如何处理文本文件中的System，而且我确定我的方法不正确:

Is this possible? I am new to python and tried something like this but Python doesn't know what to do with System in the text file and I'm sure my method isn't correct:

os.chdir('/Users/DevEnv/')

with open('RawDataFile_445.txt') as a:
    for line in a.readlines():
        j=[]
        data=line.strip()
        data1=data.split(" ")
        for i in range(0,len(data1)):
            j.append(eval(data1[i]))
        joint=j

推荐答案

您的解决方案似乎很脆弱:

Your solution seemed fragile:

• 您必须过滤标题，非数据行
• 您使用eval()确实过大且不安全.
• 使用readlines()可能会占用大量内存:读取内存中的所有数据，您无需这样做.一次只读一行.
• 您错过了写回输出文件的代码

• you have to filter headers, non-data lines
• you use eval() which is really overkill and unsafe.
• using readlines() can be very memory-hungry: reads all data in memory, you don't need to do that. Just read one line at a time.
• you miss the code to write back to the output files

我的解决方案使用正则表达式一次性提取所有数据.代码中的注释:

My solution uses regular expressions to extract all data in one go. Comments in the code:

import re

# regex to extract data line    
r = re.compile(r"\s*(\d+)\s+X=(\S+)\s+Y=(\S+)\s+Z=(\S+)")

with open('RawDataFile_445.txt') as a:

    # open all 4 files with a meaningful name
    files=[open("file_{}.txt".format(x),"w") for x in ["J","X","Y","Z"]]
    for line in a:
        m = r.match(line)
        if m:
            # line matches: write in all 4 files (using zip to avoid doing
            # it one by one)
            for f,v in zip(files,m.groups()):
                f.write(v+"\n")

    # close all output files now that it's done
    for f in files:
        f.close()

您可以通过将with open(...) as a:位替换为:

you can test it by replacing the with open(...) as a: bit by:

a="""SYSTEM

DOF=UY,UZ,RX  LENGTH=FT  FORCE=Kip

JOINT
  1  X=0  Y=-132.644  Z=0
  2  X=0  Y=-80  Z=0
  3  X=0  Y=-40  Z=0
  4  X=0  Y=0  Z=0
  5  X=0  Y=40  Z=0
  6  X=0  Y=80  Z=0
  7  X=0  Y=132.644  Z=0""".splitlines().__iter__()

模拟输入文件行(这是我回答输入文件问题的方法，以避免在系统上创建输入文件).您会看到这4个文件已创建并填满(不要忘了代码结尾的close部分)

emulating the input file lines (that's how I do to answer questions with input files, to avoid creating input files on my system). You'll see the 4 files are created and filled up (don't forget the close part at the end of the code)

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