using to determine wifi strength and display icon representation

wifi-test.py

import subprocess
temp = subprocess.Popen(args=['iwconfig wlan0 | grep -i quality'], stdout=subprocess.PIPE, shell=True)
wlan0_val, err = temp.communicate()
wlan0_strength = str(wlan0_val)
wlan0_strength = 'bb          Link Quality=5/50  Signal level=-51 dBm  \n'
cmp=wlan0_strength[25:33]
i=1
while cmp[i]!='/':
    i += 1
cmp_num = cmp[:i]
i += 1
j = i
while cmp[i]!=' ':
    i += 1
cmp_den = cmp[j:i]
try:
    num = int(cmp_num)
    den = int(cmp_den)
except:
    num, den = 0
if num > 10 and den > 10:
    try:
        wlan0_strength = num/den
    except:
        print('ERROR: set wifi indicator off')
    if wlan0_strength < .2:
        print(str(num) + '/' + str(den) + ' set wifi indicator low')
    elif wlan0_strength < .5:
        print(str(num) + '/' + str(den) + ' set wifi indicator half')
    else:
        print(str(num) + '/' + str(den) + ' set wifi indicator high')
else:
    print(str(num) + '/' + str(den) + ' set wifi indicator off')