需要从 python 中的列表中提取信息-使用 jupyter notebook

Question

I am a beginner and I am learning python for my class, The problem I am currently running into is, I am sending a ping to googles server and tracing the time it takes for it to reach back. 3 values are given for each step of the ping. I need to convert these 3 values into a average but they are apart of a string with a bunch of other useless random information that I need to sort out. I'm having trouble with separating these values from the other information.

I have tried using the split() method with new lines to get a list of each individual line and del to delete some of the redundant information, but I'm having trouble with refining it further.

import subprocess
from subprocess import check_output, Popen, call, PIPE, STDOUT 

latency  = []

p = Popen('tracert google.com', stdout = PIPE, stderr = STDOUT, shell = True)
for line in p.stdout:
    lntxt = line.decode('utf-8').rstrip()
    print(lntxt)
    words = lntxt.split('\n')
    latency.append(words)
del latency [0:4]
del latency [-4:0]
del latency [-1]
del latency [-1]

L1 = (latency)
L2 = ""
L3 = ""
for x in L1:
    L2 += str(x)
L2.split(" ms  ")

This is what happens when I run the code:

Tracing route to google.com [142.250.190.110]
over a maximum of 30 hops:

  1     2 ms     2 ms     1 ms  141.215.192.2
  2     3 ms    14 ms     2 ms  fcn-core-eth-1-4.its.umd.umich.edu 
[141.215.2.202]
  3     3 ms     2 ms     2 ms  fcn-edge-merit-primary.its.umd.umich.edu 
[141.215.2.103]
  4     4 ms    10 ms     3 ms  drbr-fairlane-d1.its.umd.umich.edu 
[141.215.2.56]
  5     3 ms     2 ms     2 ms  ae1x78.dtrt-wsudc-c1.mich.net 
[207.72.237.28]
  6    11 ms    10 ms    16 ms  ae6x14.chcg-lvl3-600w.mich.net 
[198.108.22.13]
  7    11 ms    11 ms    11 ms  192.35.170.66
  8    13 ms    12 ms    12 ms  209.85.250.189
  9    11 ms    11 ms    11 ms  142.251.60.205
 10    11 ms    11 ms    11 ms  ord37s35-in-f14.1e100.net 
[142.250.190.110]

Trace complete.
["['  1     2",
 '   2',
 '   1',
 "141.215.192.2']['  2     3",
 '  14',
 '   2',
 "fcn-core-eth-1-4.its.umd.umich.edu [141.215.2.202]']['  3     3",
 '   2',
 '   2',
 "fcn-edge-merit-primary.its.umd.umich.edu [141.215.2.103]']['  4     
4",
 '  10',
 '   3',
 "drbr-fairlane-d1.its.umd.umich.edu [141.215.2.56]']['  5     3",
 '   2',
 '   2',
 "ae1x78.dtrt-wsudc-c1.mich.net [207.72.237.28]']['  6    11",
 '  10',
 '  16',
 "ae6x14.chcg-lvl3-600w.mich.net [198.108.22.13]']['  7    11",
 '  11',
 '  11',
 "192.35.170.66']['  8    13",
 '  12',
 '  12',
 "209.85.250.189']['  9    11",
 '  11',
  '  11',
 "142.251.60.205'][' 10    11",
 '  11',
 '  11',
 "ord37s35-in-f14.1e100.net [142.250.190.110]']"]

Answer 1

you need to process each line, searching between two characters or using regular expressions in order to extract the desired value.

I give you a functional example:

from subprocess import check_output, Popen, call, PIPE, STDOUT 

latency  = []

def call_traceroute(url: str):
    p = Popen(f'traceroute {url}', stdout = PIPE, stderr = STDOUT, shell = True)
    lines = []
    for line in p.stdout:
        lines.append(line.decode('utf-8').rstrip())
    lines = lines[1:]
    print(lines)
    return lines

def extract_string_between_two_characters(original_string: str, start_character: str, end_character: str):
    return original_string[original_string.find(start_character)+len(start_character):original_string.find(end_character)]

def extract_latency(line: str):
    latency = extract_string_between_two_characters(original_string=line, start_character =") ", end_character="ms")
    return latency

all_steps = call_traceroute('google.com')
print("\n\n")
for index, step in enumerate(all_steps):
    print(f"Original Traceroute line {step}")
    latency = extract_latency(step)
    print(f"Latency in step: {index} is {latency} ms\n\n")

An output example is:

python3 latency.py
[' 1  192.168.1.1 (192.168.1.1)  10.005 ms  3.198 ms  3.406 ms', ' 2  10.0.0.1 (10.0.0.1)  4.231 ms  4.078 ms  4.376 ms', ' 3  172.16.8.193 (172.16.8.193)  4.896 ms  4.977 ms  4.772 ms', ' 4  10.220.100.48 (10.220.100.48)  9.616 ms  9.731 ms  11.255 ms', ' 5  74.125.119.226 (74.125.119.226)  11.714 ms  14.836 ms  10.961 ms', ' 6  74.125.242.161 (74.125.242.161)  11.411 ms  11.846 ms', '    74.125.242.177 (74.125.242.177)  11.894 ms', ' 7  142.250.213.125 (142.250.213.125)  11.794 ms  11.892 ms  11.388 ms', ' 8  mad07s23-in-f14.1e100.net (142.250.184.174)  13.050 ms  10.042 ms  11.020 ms']



Original Traceroute line  1  192.168.1.1 (192.168.1.1)  10.005 ms  3.198 ms  3.406 ms
Latency in step: 0 is  10.005  ms


Original Traceroute line  2  10.0.0.1 (10.0.0.1)  4.231 ms  4.078 ms  4.376 ms
Latency in step: 1 is  4.231  ms


Original Traceroute line  3  172.16.8.193 (172.16.8.193)  4.896 ms  4.977 ms  4.772 ms
Latency in step: 2 is  4.896  ms


Original Traceroute line  4  10.220.100.48 (10.220.100.48)  9.616 ms  9.731 ms  11.255 ms
Latency in step: 3 is  9.616  ms


Original Traceroute line  5  74.125.119.226 (74.125.119.226)  11.714 ms  14.836 ms  10.961 ms
Latency in step: 4 is  11.714  ms


Original Traceroute line  6  74.125.242.161 (74.125.242.161)  11.411 ms  11.846 ms
Latency in step: 5 is  11.411  ms


Original Traceroute line     74.125.242.177 (74.125.242.177)  11.894 ms
Latency in step: 6 is  11.894  ms


Original Traceroute line  7  142.250.213.125 (142.250.213.125)  11.794 ms  11.892 ms  11.388 ms
Latency in step: 7 is  11.794  ms


Original Traceroute line  8  mad07s23-in-f14.1e100.net (142.250.184.174)  13.050 ms  10.042 ms  11.020 ms
Latency in step: 8 is  13.050  ms