CODEWITHSUNDEEP
python
user3565259
user3565259

Reputation: 101

Python: Finding a negative number in a line of text from a file

I have a program that polls a servers current Wi-Fi status every minute, and saves that info to a .txt file. The output is:

*****CURRENT WIFI SIGNAL STRENGTH*****: Link Quality=57/70 Signal level=-53 dBm

The text file contains many of these lines. What I'm trying to accomplish is: -Find the signal dBm values in all the lines, and append them to an array so I can then I can do other functions such as sort and average. I can't seem to get it working quite right.

Does anyone know how to do this?

Thank you!

Upvotes: 2

Views: 1515

Answers (3)

MC93
MC93

Reputation: 799

signal_levels = []

try:
    with open("file.txt") as fh:
        lines = fh.readlines()
except IOError as err:
    # error handling

Then you can either make use of the re module:

for line in lines:
     matches = re.search(r'Signal level=(-?[0-9]+) dBm$', line)
     if matches is None:
         # possible error handling
     signal_levels.append(int(matches.group(1)))

Or without it (inspired by heinst's answer):

for line in lines:
    try:
        value = int(line.split('=')[-1].split()[0])
        signal_levels.append(value)
    except ValueError as err:
        # possible error handling

Upvotes: 2

Devin McGinty
Devin McGinty

Reputation: 15

Assuming that the signal level is the only negative number on any line you could use a regular expression with the findall function to search for all negative numbers in the file and return them as a list of strings (based on MC93's answer).

import re
f_in = open("input.txt", "r")
signal_levels = re.findall("-\d+", f_in.read())

Alternatively, you could get a list of ints with a list comprehension.

signal_levels = [int(n) for n in re.findall("-\d+", f_in.read())]

Upvotes: 1

heinst
heinst

Reputation: 8786

I would go through each line in the file and split the line at =, then get the last value, split it at the space, and then get the first value which would yield -53.

strengthValues = []
f = open("input.txt", "r")
fileLines = f.readlines()
for line in fileLines:
    lineSplit = line.split('=')
    strengthValues.append(lineSplit[-1].split()[0])
print strengthValues

Or list comprehension:

f = open("test.txt", "r")
fileLines = f.readlines()
strengthValues = [line.split('=')[-1].split()[0] for line in fileLines]
print strengthValues

Upvotes: 2

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