CODEWITHSUNDEEP
pythonvariables
AlexCCIE
AlexCCIE

Reputation: 51

How can I create second var automatically?

I parse a text file for the following line.

stp 11441 0 0 0 0

there are always 2 such line occurrences in the txt file. I am looking for the second value in the line (11441 here) and save it as a variable.

I have figured it out how to do such manipulations with only one variable. Here is the code I am using

import re
with open('cpu.txt', 'r') as file:
    for line in file:
        match = re.search('stp               \d{2,100}', line)
        if match:
            stp_queue1 = match.group().split( )[1]

However, I can't get my head around how I specify a variable (stp_queue2 in that case) for the second time match occurrence.

In other words: if the file contains 2 following lines:

stp 11441 0 0 0 0
stp 20000 0 0 0 0

then stp_queue1 should be 11441 and stp_queue2 should be 20000 respectively.

Could you please help me with that?

Upvotes: 2

Views: 68

Answers (5)

bla
bla

Reputation: 1870

If all you need is a list containing the that first number following stp this may be enough: 

with open('cpu.txt', 'r') as f:
    stp_queue = [line.split()[1] for line in f]

print(stp_queue)

If you need to check whether the line begins with stp just add that validation to the comprehension: 

with open('cpu.txt', 'r') as f:
    stp_queue = [line.split()[1] for line in f if line.startswith('stp')]

print(stp_queue)

Upvotes: 0

Aaditya Ura
Aaditya Ura

Reputation: 12669

There are many patterns you can use for this problem :

i am showing you three pattern, you can choose which you want :

first pattern :

import re

pattern=r'stp\s(\d+)'

output=[]
with open('file.txt','r') as f:
    for line in f:
        match=re.search(pattern,line)
        output.append(match.group(1))

print(output)

output:

['11441', '20000']

Pattern 2:

r'[0-9]{5}'

pattern 3:

Positive Lookbehind (?<=stp\s)

pattern=r'(?<=stp\s)\d+'

Upvotes: 2

ems
ems

Reputation: 990

Use groups in your regular expression. Please read python regex documentation

Upvotes: -1

corn3lius
corn3lius

Reputation: 4985

If you put them in a list the order is preserved and look up is as easy as stp_queue[0]

import re
stp_queue = []
with open('cpu.txt', 'r') as file:
    for line in file:
        match = re.search('stp               \d{2,100}', line)
        if match:
            stp_queue.append(match.group().split( )[1])

Upvotes: 1

Zack Tarr
Zack Tarr

Reputation: 851

You could add your values to a dictionary rather than each to its own variable. See the code below for adding each match to a dictionary with the key being stp_queue# with the number starting at 1. 

import re
dictionary={}
with open('cpu.txt', 'r') as file:
    counter=1
    for line in file:
        match = re.search('stp               \d{2,100}', line)
        if match:
           dictionary["stp_queue"+str(counter)]  = match.group().split( )[1]
           counter++
print dictionary

Then to extract the data dictionary["stp_queue1"] will return the value stored for the first match found.

More on dictionaries here: https://docs.python.org/2/tutorial/datastructures.html#dictionaries

Upvotes: 1

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