Extract Values Between Two Strings In A Text File

Lets say I have a Text file with the below content fdsjhgjhg fdshkjhk Start Good Morning Hello World End dashjkhjk dsfjkhk Start hgjkkl dfghjjk fghjjj Start Go

Solution 1:

Great problem! This is a bucket problem where each start needs an end.

The reason why you got the result is because there are two consecutive 'Start'.

It's best to store the information somewhere until 'End' is triggered.

infile =open('scores.txt','r')
outfile=open('testt.txt','w')
copy=Falsefor line in infile:

    if line.strip() == "Start":
        bucket = []
        copy=True

    elif line.strip() == "End":
        for strings in bucket:
            outfile.write( strings +'\n')
        copy=False

    elif copy:
        bucket.append(line.strip())

Solution 2:

You could keep a temporary list of lines, and only commit them after you know that a section meets your criteria. Maybe try something like the following:

infile =open('test.txt','r')
outfile=open('testt.txt','w')
copy=False
tmpLines = []
for line in infile:
    if line.strip() == "Start":
        copy=True
        tmpLines = []
    elif line.strip() == "End":
        copy=Falsefor tmpLine in tmpLines:
            outfile.write(tmpLine)
    elif copy:
        tmpLines.append(line)

This gives the output

     Good Morning
     Hello World
 Good Evening
 Good 

Solution 3:

Here's a hacky but perhaps more intuitive way using regex. It finds all text that exists between "Start" and "End" pairs, and the print statement trims them off.

import re 
infile = open('test.txt','r')
text = infile.read() 

matches = re.findall('Start.*?End',text)
for m in matches: 
    print m.strip('Start ').strip(' End')

Solution 4:

You can do this with regular expressions. This will exclude rogue Start and End lines. Here is a live example

import re

f = open('test.txt','r')
txt = f.read()
matches = re.findall(r'^\s*Start\s*$\n((?:^\s*(?!Start).*$\n)*?)^\s*End\s*$', txt, flags=re.M)

Solution 5:

If you don't expect to get nested structures, you could do this:

# match everything between "Start" and "End"
occurences = re.findall(r"Start(.*?)End", text, re.DOTALL)
# discard text before duplicated occurences of "Start"
occurences = [oc.rsplit("Start", 1)[-1] for oc in occurences]
# optionally trim whitespaces
occurences = [oc.strip("\n") for oc in occurences]

Which prints

>>>for oc in occurences: print(oc)
     Good Morning
     Hello World
   Good Evening
   Good

You can add the \n as part of Start and End if you want