read a specific string from a file in python?

Question

I want to read the above file foo.txt and read only UDE from the first line and store it in a variable then Unspecified from the second line and store it in a variable and so on. should I use read or readlines ? should I use regex for this ?? My below program is reading the entire line. how to read the specific word in the line ?

fo = open("foo.txt", "r+")
line = fo.readline()
left, right = line.split(':')
result = right.strip()
File_Info_Domain = result
print File_Info_Domain
line = fo.readline()
left, right = line.split(':')
result = right.strip()
File_Info_Intention = result
print File_Info_Intention
line = fo.readline()
left, right = line.split(':')
result = right.strip()
File_Info_NLU_Result = result
print File_Info_NLU_Result
fo.close()

furas · Accepted Answer · 2016-01-07 14:10:50Z

1

You can use readline() (without s in name) to read line on-by-one, and then you can use split(':') to get value from line.

fo = open("foo.txt", "r+")

# read first line
line = fo.readline()

# split line only on first ':'
elements = line.split(':', 1) 

if len(elements) < 2:
    print("there is no ':' or there is no value after ':' ")
else:
    # remove spaces and "\n"
    result = elements[1].strip()
    print(result)

#
# time for second line
#

# read second line
line = fo.readline()

# split line only on first ':'
elements = line.split(':', 1)

if len(elements) < 2:
    print("there is no ':' or there is no value after ':' ")
else:
    # remove spaces and "\n"
    result = elements[1].strip()
    print(result)

# close
fo.close()

edited Jan 7, 2016 at 14:10

answered Jan 7, 2016 at 13:29

furas

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9 Comments

akshay Over a year ago

I updated my code but I am getting the error as : Traceback (most recent call last): File ".\file.py", line 46, in <module> left, right = line.split(':') ValueError: too many values to unpack

tglaria Over a year ago

That's because you have too many values in the third line, it's being splitted at each :

furas Over a year ago

because you have more then one : in line and split create more then two elements - use elements = line.split(':') and then elements[1] to get element.

akshay Over a year ago

can you update that in the code. it is confusing. Is it correct - # read third line line = fo.readline() elements = line.split(':') elements[1] = elements result3 = right.strip() File_Info_NLU_Result = result3 print File_Info_NLU_Result

furas Over a year ago

btw: you asked for first and second line - third needs modification - split need another argument to slip only on first ':'.

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Tales Pádua · Accepted Answer · 2016-01-07 14:07:16Z

0

While you can use @furas response or regex, I would recommend you to use a config file to do this, instead of a plain txt. So your config file would look like:

[settings]
Domain=UDE
Intention=Unspecified
nlu_slot_details={"Location": {"literal": "18 Slash 6/2015"}, "Search-phrase": {"literal": "18 slash 6/2015"}

And in your python code:

import configparser

config = configparser.RawConfigParser()
config.read("foo.cfg")

domain = config.get('settings', 'Domain')
intention = config.get('settings', 'Intention')
nlu_slot_details = config.get('settings', 'nlu_slot_details')

answered Jan 7, 2016 at 14:07

Tales Pádua

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4 Comments

furas Over a year ago

I agree with you :) I was going to suggest json or yaml.

akshay Over a year ago

i am getting an error as : ImportError: No module named configparser

furas Over a year ago

@akshay if you use Python 2.7 try ConfigParser

Tales Pádua Over a year ago

You need to install the package. You can do it with pip

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