CODEWITHSUNDEEP
pythonparsing
Abhishek Moondra
Abhishek Moondra

Reputation: 95

how to read from a particular line upto a particular line in python

I haave a file and I want to read a specific part of it. This is the file.

..... ..... Admin server interface begins ... .... .... .... .... Admin server interface ends .... ....

I want to read the part of file between 'admin server interface begins' till 'admin server interface ends'. I found a way of doing it in perl but can't find a way in python.

in perl

while (<INP>)
{
  print $_ if(/^AdminServer interface definitions begins/ .. /^AdminServer interface definitions ends/);
}

Could anyonle please help.

Upvotes: 0

Views: 71

Answers (2)

WoJ
WoJ

Reputation: 29957

You can read the file line by line and gather what is in between your markers.

def dispatch(inputfile):
    # if the separator lines must be included, set to True
    need_separator = True
    new = False
    rec = []
    with open(inputfile) as f:
        for line in f:
            if "Admin server interface begins" in line:
                new = True
                if need_separator:
                    rec = [line]
                else:
                    rec = []
            elif "Admin server interface ends" in line:
                if need_separator:
                    rec.append(line)
                new = False
                # if you do not need to process further, uncomment the following line
                #return ''.join(rec)
            elif new:
                rec.append(line)
    return ''.join(rec)

The code above will successfully return data even if the input file does not contain the ending separator (Admin server interface ends). You can amend the last return with a condition if you want to catch such files:

if new:
    # handle the case where there is no end separator
    print("Error in input file: no ending separator")
    return ''
else:
    return ''.join(rec)

Upvotes: 3

TerseCode
TerseCode

Reputation: 45

If the file isn't very big and you are not concerned about memory consumption, you can write this simple solution:

from os.path import isfile
def collect_admin_server_interface_info(filename):
    """ Collects admin server interface information from specified file. """
    if isfile(filename):
        contents = ''
        with open(filename, 'r') as f:
            contents = file.read()
        beg_str = 'Admin server interface begins'
        end_str = 'Admin server interface ends'
        beg_index = contents.find(beg_str + len(beg_str))
        end_index = contents.find(end_str)
        if beg_index == -1 or end_index == -1:
             raise("Admin server interface not found.")
        return contents[beg_index : end_index]
    else:
        raise("File doesn't exist.")

This method will try to return a single string containing administrator server interface information.

Upvotes: 1

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