Today: wordcount -top exercise, modules, urllib example, how the internet works

Recall: d.items()

• dict.items() returns list-like of tuples length-2
• Each tuple (key, value)
• Thus dict.items() gets the whole dict contents in one step

>>> d = {'a': 'alpha', 'g': 'gamma', 'b': 'beta'}
>>> 
>>> d.items()
dict_items([('a', 'alpha'), ('g', 'gamma'), ('b', 'beta')])
>>> 

Put It All Together - WordCount + Sorted

Look at wordcount project, apply custom sorting to the output stage.

Wordcount Items = (word, count)

• Wordcount has a "counts" dict, key is a word, value is its count
• Access as counts.items()
• Pairs in items list: (word, count)
• Use "items" as var name for items
• Use "pair" as lambda parameter, (word, count)

>>> items = [('zebra', 1), ('ant', 3), ('elk', 11), ('bear', 4),
('cat', 2)]

Items Exercise Warmup

• Warmup for -top code next section
• Copy that items list into interpreter, try these code exercises (done similar before)
• Questions we could ask of the items - demo or you-try-it
• 1. How to sort items in increasing order by word (easy!)
• 2: How to sort items in increasing order by count?
• 3. How to sort items in decreasing order by count?
• 4: How to access the pair with the largest count?

>>> sorted(items)
[('ant', 3), ('bear', 4), ('cat', 2), ('elk', 11), ('zebra', 1)]
>>> sorted(items, key=lambda pair: pair[1])   # increasing count
[('zebra', 1), ('cat', 2), ('ant', 3), ('bear', 4), ('elk', 11)]
>>> sorted(items, key=lambda pair: pair[1], reverse=True)  # decreasing
[('elk', 11), ('bear', 4), ('ant', 3), ('cat', 2), ('zebra', 1)]
>>> max(items, key=lambda pair: pair[1])   # max count
('elk', 11)

Wordcount - Top-Count - Lambda

Here is the WordCount project we had before. This time look at the print_counts() and print_top() functions.

> wordcount.zip

print_counts() Feature Output

Here is the output of the regular print_counts() function, which prints out in alphabetic order. Output looks like:

$ python3 wordcount.py poem.txt 
are 2
blue 2
red 2
roses 1
violets 1
$

print_counts() Solution

This is the standard dict-output sorted loop. The first bit of code uses d.keys(), which is ok. The alternate solution shown uses d.items() which is neat if you want to use it.

def print_counts(counts):
    """
    Given counts dict, print out each word and count
    one per line in alphabetical order, like this
    aardvark 1
    apple 13
    ...
    """
    for word in sorted(counts.keys()):
        print(word, counts[word])

    # Alternately use .items() to access all the key/value
    for key, value in sorted(counts.items()):
        print(key, value)

print_top() Feature Output

The print_top(counts, n) function - print the n most common words in decreasing order by count.

$ python3 wordcount-solution.py -top 10 alice-book.txt 
the 1639
and 866
to 725
a 631
she 541
it 530
of 511
said 462
i 410
alice 386

How to write the code for that?

print_top() Exercise

def print_top(counts, n):
    """
    Given counts dict and int N, print the N most common words
    in decreasing order of count
    the 1045
    a 672
    ...
    """
    items = counts.items()
    # Could print the items in raw form, just to see data
    # print(items)
    pass
    # Your code - my solution is 3 lines long, but it's dense!
    # Sort the items with a lambda so common words are first.
    # Then print just the first N word,count pairs with slice

Coding Technique: Print What You Have

• Look at print_top() function - exercise to write code to print top words
• How to proceed?
• Technique: print what data you have just above where the code goes
• This is a way to get un-stuck because..
• 1. Python is able to print in a plain-looking way dicts/lists/strings
  So you can print out your data structures without extra coding
• 2. Looking at a concrete example, it's easier to see what the next step is
• Recall: dict.items() - random order of word/count pairs
  [('sister', 12), ('rabbit', 5), ...]
• How sort these to print the largest count first?
• This code is incredibly short and powerful

print_top() Solution

Here's the lines - sort by count decreasing order. Then slice to take the top n.

    # 1. Sort largest count first
    items = sorted(items, key=lambda pair: pair[1], reverse=True)
    # 2. Slice to grab first N
    for word, count in items[:n]:
        print(word, count)

Modules and Modern Coding

Modules hold code for common problems, ready for your code to use. We say that you build your code "on top of" the libraries. Modern coding is part custom, and part building on top of module code.

We ♥ Modules

• Question while coding:
  Is part of this solved in a module already?
• Using module code you didn't have to write is very attractive
• (This is kind of a no-brainer case to make!)
• Somebody else wrote it, you can just use it
• It's well tested
• It has real docs
• Your teammates may already be familiar with it
• CS106A we see this "module" theme a little
  CS106A needs to cover fundamentals
  loops, strs, dicts, files ..
  Courses beyond CS106A, you will probably spend more time using modules

Module = Name + Code

• A Python module contains lots of functions, solving common problems
• Every module has a name
• e.g. "math" module contains math functions
• e.g. "random" module contains functions for pseudo-random numbers=
• e.g. "urllib" module contains functions for urls and web requests

Syntax 1: import math

• To use a module, include a import math line
• Import the module by its name
• Typically these are grouped near the top of your file

Syntax 2: math.sqrt(2)

• On later lines, refer to functions in the module with a dot
• e.g. math.sqrt(2)
• e.g. random.randrange(10)
• Readable: in this way, it's clear when calling a function..
  that it is coming from that module
• There are other ways of doing import
• This form is simplest: import math .. math.sqrt()

>>> import math
>>> math.sqrt(2)  # call sqrt() fn
1.4142135623730951
>>> math.sqrt

>>> 
>>> math.log(10)
2.302585092994046
>>> math.pi       # constants in module too
3.141592653589793

Quit and restart the interpreter without the import, see common error:

>>> # quit and restart interpreter
>>> math.sqrt(2)  # OOPS forgot the import
Traceback (most recent call last):
NameError: name 'math' is not defined
>>>
>>> import math
>>> math.sqrt(2)  # now it works
1.4142135623730951

Module = Dependency

• When you write code using a module
• Your code now depends on that module's existence
• If that module disappeared, your code would stop working

1. "Standard" Modules - Fine

• Standard = included/maintained as part of Python3 install
• These are the best modules to use
• Can rely on this module now and in the future
  Very rare for a module to be dropped
• No separate install is required
• The standard module is installed when python is installed

Many Standard Modules

• Do not: memorize whole list of modules
• Do: check the list for help when starting a project
• Standard Python Modules List
• A few examples...
• csv module to read CSV files, such as produced by Excel
• math module of math functions, e.g. math.cos()
• email module for creating and parsing email messages
• random module for creating pseudo random numbers
• os module for listing directories, creating files
• datetime module of calendar functions
• zipfile module for reading/creating .zip files
• urllib module for making http requests, using data

2. Non-Standard "pip" Modules - Depends

Other modules are valuable but they are not a standard part of Python. For code using non-standard module to work, the module must be installed on that computer via the "pip" Python tool. e.g. for homeworks we had you pip-install the "Pillow" module with this command:

$ python3 -m pip install Pillow
..prints stuff...
Successfully installed Pillow-5.4.1

A non-standard module can be great, although the risk is harder to measure. The history thus far is that popular modules continue to be maintained. Sometimes the maintenance is picked up by a different group than the original module author.

Aside: Security of Pip Module

When you install a module on your machine from somewhere - you are trusting that code to run on your machine. In very rare cases, bad guys have tampered with modules to include malware in the module. Be more careful if installing a little used module. In contrast, python itself or standard modules like urllib are very safe as so many people use them.

Module Documentation - "Docs"

• Every module has formal "documentation" - "docs"
• Explain what functions do
• The "abstraction" of each function
  what it does
  how to call it
• Demo web search: "python math module"
• python.org - the official home of python docs
  Official python.org math docs
  Watch out for SEO
  Search Engine Optimization
  Some possibly lame site tries to get a better search ranking

Hacker: Use dir() and help() (optional)

• Feel like a hacker, use dir() and help() on module
• In the interpreter >>>
• dir(module) - shows a list of all the defs in the module
• help(module.fn) - shows some help text for that function
• The """Pydoc""" we write to describe each function
• That Pydoc is what help() returns (demo later)
• Names starting with double-underbar = internal thing you probably don't need
  e.g. __file__, __loader__

>>> import math
>>> dir(math)
['__doc__', '__file__', '__loader__', '__name__', '__package__', '__spec__', 'acos', 'acosh', 'asin', 'asinh', 'atan', 'atan2', 'atanh', 'ceil', 'copysign', 'cos', 'cosh', 'degrees', 'e', 'erf', 'erfc', 'exp', 'expm1', 'fabs', 'factorial', 'floor', 'fmod', 'frexp', 'fsum', 'gamma', 'gcd', 'hypot', 'inf', 'isclose', 'isfinite', 'isinf', 'isnan', 'ldexp', 'lgamma', 'log', 'log10', 'log1p', 'log2', 'modf', 'nan', 'pi', 'pow', 'radians', 'remainder', 'sin', 'sinh', 'sqrt', 'tan', 'tanh', 'tau', 'trunc']
>>>
>>> help(math.sqrt)
Help on built-in function sqrt in module math:

sqrt(x, /)
    Return the square root of x.
>>>
>>> help(math.cos)
Help on built-in function cos in module math:

cos(x, /)
    Return the cosine of x (measured in radians).

How to Create Your Own Module?

You already have! A regular old foo.py file is a module.

wordcount.py Is a Module

How hard is it to write a module? Not hard at all. A regular Python file we have written works as a module too with whatever defs the foo.py file has.

Consider the file wordcount.py in wordcount.zip

Forms a module named wordcount

• Suppose you have built some useful functions
• Someone else in your lab wants to use them....
  Them pasting in their own copy is not ideal
• What does a module contain?
• We have wordcount.py
• python3 wordcount.py - runs main()
• wordcount.py is also a module named just "wordcount"
• Think of all the defs in wordcount: read_counts(), clean(), print_counts(),
• import works on wordcount (in the same directory)
• Access functions as module.xxx just like usual
• Run python interpreter in wordcount directory to try this
• Try importing wordcount, calling the read_counts() function
• Call wordcount.clean()

Try this demo in the wordcount directory

>>> # Run interpreter in wordcount directory
>>> import wordcount
>>>
>>> wordcount.read_counts('test1.txt')
{'a': 2, 'b': 2}

• A module/file contains many defs
• Can import a module/file, call its defs:
• module.fn_name()
• Style: for a function to be usable from another module...
  it should take in data as parameters and return a value
  i.e. black box style
  we've done this all along, see now the bigger picture
• Babygraphics project:
  treats babynames.py as a module
  import babynames
  calls babynames.read_files()

dir() and help() work on wordcount Too

• Look at wordcount.py, look at the functions
• dir() and help() work here too
• See where the """Pydoc""" goes!

>>> dir(wordcount)
['__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__spec__', 'clean', 'main', 'print_counts', 'print_top', 'read_counts', 'sys']
>>> 
>>> help(wordcount.read_counts)

Help on function read_counts in module wordcount:

read_counts(filename)
    Given filename, reads its text, splits it into words.
    Returns a "counts" dict where each word
    is the key and its value is the int count
    number of times it appears in the text.
    Converts each word to a "clean", lowercase
    version of that word.
    The Doctests use little files like "test1.txt" in
    this same folder.
...

The text you put in """Pydoc""" per function .. feeds into Python help() (and like systems in PyCharm) automatically. A win!

Babynames / Babygraphics Integration

The code in babygraphics.py iports babynames to call its read_files() function. Here is what the code looks like in babygraphics. This works because the two files are in the same folder.

# 1. In the babygraphics.py file
import babynames

...

    # 2. Call the read_files() function                                                                  
    names = babynames.read_files(FILENAMES)

Module Example: urllib

• Look at how web pages work
• Then play with urllib

How Does The Web Work?

• The web browser app has url ("client" side)
• Web server is running on some machine ("server" side)
• Browser sends GET request to server
• Server gets request, sends back HTML response data
• HTML is a text code
• Browser "renders" the HTML on screen
• Common request/response data types: HTML JPEG PNG GIF SVG
• Video formats MPEG4 h.265 (crazy patent problems)
• New open format "AV1" .. you heard it here first!
• Demo:
  Visit python.org or sfgate.com or whatever
  Right-click on page, "View Source" to see the HTML text that makes a web page
• Think of all the surfing you have done .. HTML code defines each page

HTML

Here is the HTML code for is plain text with a bolded word in it, tags like <b> mark up the text.

This <b>bolded</b> text

Go to python.org. Try view-source command on this page (right click on page). Search for a word in the page text, such as "whether" .. to find that text in the HTML code.

Thing of how many web pages you have looked at - this is the code behind those pages. It's a text format! Lines of unicode chars!

urllib Demo

• Python code to request an HTML page by url
• urllib - making requests to a server, getting back data
• An example of using a standard module
• docs - urllib.request docs on python.org
• Makes a URL look like a local file mostly
• Read the text of the web page
• Use s.find() to display a fragment of it

>>> import urllib.request
>>> f = urllib.request.urlopen('http://www.python.org/')
>>> text = f.read().decode('utf-8')
>>> text.find('Whether')
26997
>>> text[26997:27100]
"Whether you're new to programming or an experienced developer, it's easy to learn and use Python.
\r\n"

• f.read() works once, returning bytes
• decode('utf-8') decode raw bytes -> unicode string
• Does not always work, they may be blocking python on purpose
• f.read() - all the bytes
• r.read(300) - just first 300 bytes
• Can try http: or https: for these

# without >>>, for copy/paste
import urllib.request
f = urllib.request.urlopen('http://www.python.org/')
text = f.read().decode('utf-8')

Data From the Web vs. Files

• Very often data is drawn from file, into your program .. parse to list dict ..
• New picture: data is drawn from a URL
• The parsing list/dict logic is the same as ever

How Does The Internet work?

Now does the Internet work? I pulled these slides together I had laying around from another class. Neat to see how something you use every day works.

Internet - TCP/IP Standards

• Internet - world-wide network built on open standards
• Open standards: TCP, IP, HTML, JPEG, PNG
• These are vendor neutral - unbelievably successful pattern
  -No license required
  -No patents required
  -Brings in a lot of participation
• Vendor-proprietary "internet" attempts pre-TCP/IP failed
• One of the most valuable inventions of recent history
  -Important lesson about open standards

1. Packets

• Say we have 50KB image.jpg
• 50,000 bytes
• How to send the image.jpg on the wire?
• Use packets
• Divide bytes of image.jpg into packets
• Say each packet is 1500 bytes (a common size)
• Then image.jpg divides into about 32 packets
• Network transmits one packet at a time

Sending One Packet

• An over simplification
• Look at transmission of one 1500 byte packet
• Each byte is 8 bits, e.g. 0 1 1 0 1 0 1 0
  -Go through all the bits, from left to right
  -For each 1, put 3 volts on the wire
  -For each 0, put 0 volts on the wire
• Modern ethernet is runs at at least 100 million bits per second
  -aka 100 mbps
• In reality, there is more complex scheme than 3-volts/0-volts
• Wifi sends the 0/1 data on a radio channel
  -The encoding is more complex
  -But you get the idea

IP Address

• Every computer on the internet has an IP address
• Here looking at IP v4 addresses, v6 addrs some day in the future
• e.g. 171.64.64.166
• IP addr is exactly 4 bytes (4 1-byte numbers)
• Left part encodes "neighborhood" on internet
• Just like phone, 650-725-0000
• e.g. 171.64.xxx.xxx generally Stanford campus
• e.g. 171.64.64.xxx my floor of Gates building
• Cannot just make up an IP addr, depends on location

Sandra Bullock Blooper

TCP/IP blooper in this video of "The Net"...

video

Blooper: in the video the IP address is shown as 75.748.86.91 - not a valid IP address! Each number should be 1 byte, 0..255

Router

• A computer typically connects to a router for service
  -We'll say the router is "upstream"
• The router provides the internet service, handling the computer's packets
• Typically when you connect to wi-fi, you get a router too
• The router will assign a temporary IP address to the computer
• The router typically has the IP address ending with ".1"

The most common way for a computer to be "on the internet" is to establish a connection with a "router" which is already on the internet. The computer establishes a connection via, say, wifi to communicate packets with the router. The router is "upstream" of the computer, connecting the computer to the whole internet.

IP Packet - Hopping

• For a computer to send a packet:
• Label it with the IP address of the source and destination
• Send it to local router
• Router in turn sends it on to bigger router
• The packet proceeds .. hop hop hop .. over to final destination

Lots of Packet Hops

The packet is passed from router to router - called a "hop". There might be 10 or 20 hops in a typical internet connection.

Router Lessons

• Each router knows enough to figure the next hop, not the whole route
• There is no "center" of the internet that knows everything
• The initiating computer does not typically know anything, delegating to its router
• "Core" routers, towards the middle, bigger, fancier, more connections
• Routers measure connection functionality/breakage all the time
  -Choose alternative routes in real time from breakage, congestion
  -e.g. a backhoe breaks an important link, routers re-route in realtime
• Routers are a distributed, collaborative system
  -Each does its part, cooperatively solving the whole thing
  -VS. centralized/top-down system

The routing of a packet from your computer is like a capillary/artery system .. your computer is down at the capillary level, your packet gets forwarded up to larger and larger arteries, makes its way over to the right area, and then down to smaller and smaller capillaries again, finally arriving at its destination.

Note: Special "Local" IP Addresses

• Note that 10.x.x.x and 192.168.x.x addresses are special "local" IP addresses
• These addresses are not valid out on the internet at large
• They are used within an organization but not outside it
• These are translated to a real IP addr as a packet makes its way
• Frequently given out by Wi-Fi routers .. why I mention them

What Does it Mean to Be On the Internet?

• On the internet - e.g. connect to a Wi-Fi router
• 1. Computer connects to an upstream router to handle traffic. Most Wi-Fi access points combine Wi-Fi radios and a router.
• 2. The router typically gives the computer an IP address to use
• The computer cannot pick an arbitrary IP address, since the left part of the address depends on the location on the internet ... details known by the router
• Also, you don't want to pick an IP address in use by someone else, so the router gives you a known good one
• 3. DHCP "Dynamic Host Configuration Protocol" - automatically configure network settings to work locally. Computers very often use this feature to get needed network configuration from the router automatically.

So what does it mean for a computer to be on the internet? Typically it means the computer has established a connection with a router. The commonly used DHCP standard (Dynamic Host Configuration Protocol), facilitates connecting to a router; establishing a temporary connection, and the router gives your computer an IP address to use temporarily. Typically DHCP is used when you connect to a Wi-Fi access point.

Demo: Your Internet

Bring up the networking control panel of your computer. It should show what IP address you are currently using and the IP address of your router. You will probably see some text mentioning that DHCP is being used. Your computer will likely have a local IP address, just used while you're in this room.

Demo: Ping

"Ping" is an old and very simple internet utility. Your computer sends a "ping" packet to any computer on the internet, and the computer responds with a "ping" reply (not all computers respond to ping). In this way, you can check if the other computer is functioning and if the network path between you and it works. As a verb, "ping" is also used in regular English this way .. not sure if that's from the internet or the other way around.

Experiment: Most computers have a ping utility, or you can try "ping" on the command line (works on the Mac, Windows, and Linux). Try pinging www.google.com or pippy.stanford.edu. Not all computers respond to ping. Type ctrl-c to terminate ping.

Milliseconds fraction of a second used for the packet to go and come back. 1 ms = 1/1000 of a second. Different from bandwidth, this "round trip delay".

Here I run the "ping" program for a few addresses, see what it reports

$ ping www.google.com  # I type in a command here
PING www.l.google.com (74.125.224.144): 56 data bytes
64 bytes from 74.125.224.144: icmp_seq=0 ttl=53 time=8.219 ms
64 bytes from 74.125.224.144: icmp_seq=1 ttl=53 time=5.657 ms
64 bytes from 74.125.224.144: icmp_seq=2 ttl=53 time=5.825 ms
^C                            # Type ctrl-C to exit
--- www.l.google.com ping statistics ---
3 packets transmitted, 3 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 5.657/6.567/8.219/1.170 ms
$ ping pippy.stanford.edu
PING pippy.stanford.edu (171.64.64.28): 56 data bytes
64 bytes from 171.64.64.28: icmp_seq=0 ttl=64 time=0.686 ms
64 bytes from 171.64.64.28: icmp_seq=1 ttl=64 time=0.640 ms
64 bytes from 171.64.64.28: icmp_seq=2 ttl=64 time=0.445 ms
64 bytes from 171.64.64.28: icmp_seq=3 ttl=64 time=0.498 ms
^C
--- pippy.stanford.edu ping statistics ---
4 packets transmitted, 4 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 0.445/0.567/0.686/0.099 ms

Traceroute

• On the mac, just open a terminal as shown below
• How to do: traceroute on windows
• See series of hops
• First few hops in your IP neighborhood
• Farther away hops .. more milliseconds
• Note New York, London .. big jump in milliseconds
• Hops does not go up linearly with distance
• East bay - 30 miles from Stanford - 11 hops
• Russia - 10000 miles from Stanford - 19 hops

Traceroute is a program that will attempt to identify all the routers in between you and some other computer out on the internet - demonstrating the hop-hop-hop quality of the internet. Most computers have some sort of "traceroute" utility available if you want to try it yourself (not required). On Windows it's called "tracert" in Windows Power Shell, and it does not suppor the "-q 1" option below, but otherwise works fine.

Some routers are visible to traceroute and some not, so it does not provide completely reliable output. However, it is a neat reflection of the hop-hop-hop quality of the internet.

Traceroute codingbat.com

codingbat.com is housed in the east bay - 13 hops we see here. The milliseconds listed is the round-trip delay.

$ traceroute -q 1 codingbat.com
traceroute to codingbat.com (173.255.219.70), 64 hops max, 52 byte packets
 1  rt-ac68u-b3f0 (192.168.1.1)  7.152 ms
 2  96.120.89.177 (96.120.89.177)  9.316 ms
 3  24.124.159.189 (24.124.159.189)  9.638 ms
 4  be-232-rar01.santaclara.ca.sfba.comcast.net (162.151.78.253)  9.775 ms
 5  be-39931-cs03.sunnyvale.ca.ibone.comcast.net (96.110.41.121)  31.753 ms
 6  be-3202-pe02.529bryant.ca.ibone.comcast.net (96.110.41.214)  10.273 ms
 7  ix-xe-0-1-1-0.tcore1.pdi-paloalto.as6453.net (66.198.127.33)  10.570 ms
 8  if-ae-2-2.tcore2.pdi-paloalto.as6453.net (66.198.127.2)  11.344 ms
 9  if-ae-5-2.tcore2.sqn-sanjose.as6453.net (64.86.21.1)  13.555 ms
10  if-ae-1-2.tcore1.sqn-sanjose.as6453.net (63.243.205.1)  11.583 ms
11  216.6.33.114 (216.6.33.114)  11.938 ms
12  if-2-4.csw6-fnc1.linode.com (173.230.159.87)  14.833 ms
13  li229-70.members.linode.com (173.255.219.70)  11.549 ms

Traceroute Serbia

A random Serbian address - 31 hops - the farthest thing I could fine. See the extra delay where the packets go across the Atlantic - I'm guessing hop 16. The names there may refer to Amsterdam and France. Note that the packets are going at a fraction of the speed of light here - a fundamental limit of how quickly you can get a packet across the earth.

$ traceroute -q 1 yujor.fon.bg.ac.rs
traceroute to hostweb.fon.bg.ac.rs (147.91.128.13), 64 hops max, 52 byte packets
 1  rt-ac68u-b3f0 (192.168.1.1)  9.136 ms
 2  96.120.89.177 (96.120.89.177)  9.608 ms
 3  24.124.159.189 (24.124.159.189)  20.184 ms
 4  be-232-rar01.santaclara.ca.sfba.comcast.net (162.151.78.253)  15.058 ms
 5  be-39911-cs01.sunnyvale.ca.ibone.comcast.net (96.110.41.113)  11.050 ms
 6  be-3411-pe11.529bryant.ca.ibone.comcast.net (96.110.33.94)  11.294 ms
 7  be3111.ccr31.sjc04.atlas.cogentco.com (154.54.11.5)  10.420 ms
 8  be2379.ccr21.sfo01.atlas.cogentco.com (154.54.42.157)  20.021 ms
 9  be3110.ccr32.slc01.atlas.cogentco.com (154.54.44.142)  37.200 ms
10  be3037.ccr21.den01.atlas.cogentco.com (154.54.41.146)  36.318 ms
11  be3035.ccr21.mci01.atlas.cogentco.com (154.54.5.90)  49.991 ms
12  be2831.ccr41.ord01.atlas.cogentco.com (154.54.42.166)  66.591 ms
13  be2718.ccr22.cle04.atlas.cogentco.com (154.54.7.130)  67.178 ms
14  be2993.ccr31.yyz02.atlas.cogentco.com (154.54.31.226)  77.369 ms
15  be3260.ccr22.ymq01.atlas.cogentco.com (154.54.42.90)  86.026 ms
16  be3042.ccr21.lpl01.atlas.cogentco.com (154.54.44.161)  152.559 ms
17  be2183.ccr42.ams03.atlas.cogentco.com (154.54.58.70)  161.324 ms
18  be2813.ccr41.fra03.atlas.cogentco.com (130.117.0.122)  164.945 ms
19  be2960.ccr22.muc03.atlas.cogentco.com (154.54.36.254)  172.507 ms
20  be2974.ccr51.vie01.atlas.cogentco.com (154.54.58.6)  197.670 ms
21  be3463.ccr22.bts01.atlas.cogentco.com (154.54.59.186)  181.075 ms
22  be3261.ccr31.bud01.atlas.cogentco.com (130.117.3.138)  184.336 ms
23  be2246.rcr51.b020664-1.bud01.atlas.cogentco.com (130.117.1.14)  189.231 ms
24  149.6.182.114 (149.6.182.114)  182.364 ms
25  amres-ias-amres-gw.bud.hu.geant.net (83.97.88.6)  191.607 ms
26  amres-mpls-core----amres-ip-core-amres-ip.amres.ac.rs (147.91.5.144)  187.181 ms
27  *
28  stanica-134-241.fon.bg.ac.rs (147.91.134.241)  204.945 ms
29  stanica-134-250.fon.bg.ac.rs (147.91.134.250)  192.673 ms
30  stanica-134-250.fon.bg.ac.rs (147.91.134.250)  193.978 ms
31  stanica-134-250.fon.bg.ac.rs (147.91.134.250)  193.032 ms !Z

TCP/IP Summary Picture