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OPS435 Python Lab 1

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LAB OBJECTIVES
= LAB OBJECTIVES =
:In this lab, you will first select and install a current distribution of Linux to be used as in a host machineVirtual Machine on your external SSD. You will NOT be required to setup Virtual Machines for do all of your future work within this lab VM (that will be covered in a future labincluding quizzes!). You will then setup your Python scripting environment on your host machine. This environment , including the setup the of '''python''' libraries and will also include the setup of a user-friendly interactive Python environment called '''ipython'''. You will also install additional framework tools (such as '''git''', '''vim''', and '''tmux''') to be used in later labs.
:After selecting an appropriate text editing editor to use, then you will start to create '''Python''' scripts to learn basic operations such as:'''printing text''', '''using objects''', and performing '''math operations'''.<br><br>
<blockquote><ul><li>x</li></ul></blockquote>= INVESTIGATION 1: INSTALLING LINUX VM=
= INVESTIGATION == PART 1: INSTALLING LINUX- Installing Your Linux Distribution ===
=== PART 1 <!- INSTALLING YOUR LINUX DISTRIBUTION ===- Try to use tables and simplify the layers of WIKI to make top links less verbose to students --> :Centos 7 - release 1810 will be used for this course. The purpose for this is to allow you to use a consistent and stable '''RedHat''' based OS, and to lower the amount of new linux distros that you need to learn. : Most of you will likely use the school's Windows machines with the Vmware hypervisor. It is also possible to use your own computer, but check with your professor before you do that. :Centos 7 comes with python 2.7, for this course we will be primarily using Python3. However, not practicing python 2.7 would be a mistake, since so many programs and operating systems still depend on Python2. It is recommended that students note general improvements/differences in Python2 and Python3.
<!-- Try to use tables and simplify the layers of WIKI to make top links less verbose to students -->
:Since Python runs '''<u>independentlyCentos 7 VM Details / Minimum Requirements:</u> regardless the of the Linux distribution, you have some flexibility of which Linux OS to use. Below is a table displaying the characteristics of the Centos vs Fedora distributions and related Python packages.'''
::*'''Name:''' centos7
::*'''Boot media / Installation:''' CentOS7 Full Install DVD
:::*Download at Seneca College: CentOS 7 Full Install DVD (image file): http://belmont.senecacollege.ca/pub/centos/7/isos/x86_64/CentOS-7-x86_64-DVD-1810.iso
:::*Download outside Seneca College: http://mirror.csclub.uwaterloo.ca/centos/7/isos/x86_64/CentOS-7-x86_64-DVD-1810.iso
::*'''Disk space:''' 50GB
::*'''CPUs:''' 4 (Number of processors: 1, Number of cores per processor: 4)
::*'''Internal Memory:''' 8GB
::*'''Environment:''' GNOME Desktop
<table border="1" cellspacing="0" cellpadding="5" style="margin-left:25px;margin-right:25px;" >
<tr><td>'''Linux Distribution'''</td><td>'''Characteristics'''</td><td>'''Python Version'''</td></tr>
<tr><td valign="top">'''Centos7'''</td><td valign="top">The stable version of Centos 7 - release 1161 will be chosen(tested) to be supported for this course. This is to keep the ops stream on red hat based systems, lower the amount of new linux distros that need to be learned by students. This should be the default choice for this course, as it allows for the course to run longer before getting outdated with new software and updates.<br><br>Current version (Belmont Server):<br>http://belmont.senecacollege.ca/pub/centos/7/isos/x86_64/CentOS-7-x86_64-DVD-1611.iso<br><br>Current Version (External Source):<br> http://mirror.csclub.uwaterloo.ca/centos/7/isos/x86_64/CentOS-7-x86_64-Everything-1611.iso<br><br></td><td valign="top">Centos 7 comes with python 2.7, which means that it is not optimal out for the box for teaching this course. However not teaching python 2.7 would be a mistake since so many programs and operating systems still depend on python 2. It would be good to note some changes and encourage new work to be done in python3 while paying attention to specific projects that work only with python 2.</td></tr>
<tr><td valign="top">'''Fedora'''</td><td valign="top">Fedora will always be the slightly harder distribution to support for a course, so it would be great to have an alternative Linux distribution that is stable. The Fedora distribution has a much larger set of packages throughout its repositories, while this is usually not advantageous for a server context, it can work very well with developers. As students write code they may want more customised environments and coding applications, some of these applications may be harder to get on a server distribution. The other benefit to using Fedora is gaining experience using newer software, by practicing with newer software, students will be exposed to changes they will see in much later Centos releases.<br><br>Current Version (External Source):<br> https://download.fedoraproject.org/pub/fedora/linux/releases/25/Workstation/x86_64/iso/Fedora-Workstation-Live-x86_64-25-1.3.iso<br><br></td><td valign="top">The most recent version of Fedora is a great pick for python development since they've switched the default python installed to python3, which is primarily what this course is about. However,this may cause issues as we get to Ansible or Openstack so we will have to cover the differences between python2 and python3 including a python2 installation on Fedora.</td></tr></table>
<!--==== Environment Setup ====
:'''Perform the following steps:'''
:#Regardless of the Linux distribution you decide to use that is used for this course, this these lab will be using and referring to the current version of '''Centos7CentOS 7''', and install the (Graphical Desktop ) for our host main Linux machine. When creating your VM, refer to the '''Details / Minimum Requirements''' section above for assistance. :#Install CentOS 7 VM selecting the default partitions. When you have finished the installation of Centos7CentOS 7, you may move on proceed to the next stepsstep.<blockquote style="margin-left:35px;">{{Admon/important|style="padding-left:25px"|Unit Feedback Scripts|Each '''Part''' (within an 'Investigation) is referred to as a '''Unit'''. Each Unit will require that the student download and run a '''Unit Feedback Script''', which provides the OPS435 student "real-time feedback" of their completed work.<br>This feedback is not considered to be perfect or fool-proof; however, it may provide feedback (hints) in case a student gets stuck or experiences an error when performing administration tasks or when creating their Python scripts. These unit feedback scripts can also be used to confirm that the student's Python script is on the right track, and provide a consistent record of their Python scripting progress throughout their labs.}}</blockquote>
<blockquote style="margin!-left:35px;">{{Admon/important|style="padding-left:25px"|Unit Evaluation Scripts|Each '''Part''' (within an 'Investigation) is referred to as a '''Unit'''. Each Unit will require that the student download and run a '''Unit Evaluation Script''', which can be used to look at a student's Python scripts that was created in order to provide "real-time feedback".<br>This feedback is not considered to be perfect or fool-proof; however, it may provide feedback (hints) in case a student gets stuck or experiences an error when running thier Python scripts. These unit evaluation scripts can also be used to confirm that the student's Python script is on the right track, and provide a consist record of their Python scripting progress throughout their labs.<br><br>}}</blockquote> <ol><li value="23" style="margin-left:25px;">Issue the following commands (as a regular user) in order to setup, download and run the first unit evaluation feedback script:<br><br></li></ol><blockquote><blockquote><sourcelang="bash">
mkdir -p ~/ops435/lab1/
cd ~/ops435/lab1/
pwd # <-- i.e. confirm that you are in the correct directory
ls CheckLab1.py || wget matrixhttps://raw.senecacollegegithubusercontent.cacom/~acoatleySeneca-willisCDOT/ops435/master/LabCheckScripts/CheckLab1.pypython python3 ./CheckLab1.py -f -v lab0a</source></blockquote></blockquoteli><ol><li value="3" style="margin-left:25px;">Before moving on to the next step make sure you identify any and all errors in "lab1a.py"from the check script.<br>When the check script tells you everything is "ok" for "lab0a", you may proceed to the next step.<br><br></li><li style="margin-left:25px;">Make notes for all of your Investigation 1 (part1) observations in your lab log book, and proceed to the next section</liol></ol-->
=== Part PART 2 - SETTING UP YOUR PYTHON ENVIRONMENT FOR OPS435 LABS Setting up Your Python Environment For Labs ===
In order to learn how to use python on your Linux machine, it is important to setup your Linux environment and learn how to interact with a Python shell. The following should be done on a terminal as the superuser (i.e. root).
:'''Perform the following steps:'''
:#The first step is to update your entire system. <sourcelang="bash">
yum update
</source>
:#Install extra packages for enterprise linux:<sourcelang="bash">
yum install epel-release
</source>
:#Next install applications that we needrequired, first Python version 3 and version 2:<sourcelang="bash">
yum install python34 python34-devel # Install python3.4 and python3.4 development libraries
yum install python python2-devel # Install python2.7 and python2.7 development libraries
</source>
:#We now need to create a link to python3.4:<source lang="bash">cd /binln -s python3.4 python3</source>:#Next, you will install a couple of useful applications called '''tmux''' and '''screen'''. They are referred to as '''terminal multiplexers'''. If you plan to spend a lot of time in the terminal, this powerful tool will help you get it done. Lets install it and plan to use it later:<sourcelang="bash">
yum install screen tmux && ln -s /usr/bin/true /etc/sysconfig/bash-prompt-screen
</source>
:# You will now set Set your hostname to the Linux Distribution we are usingin case you did not set it correctly during the install process:<sourcelang="bash">
hostnamectl set-hostname centos7 # Set your hostname to distribution-name
</source>
::You will be required to use a text editor in order to create and modify your Python scripts. There are many text editors that provide various features to become more comfortable and productive during your Python coding sessions. ::Below is a listing of several common text editors and their features.<blockquote><blockquotestyle="margin-left:35px;">{{Admon/importanttip|style="padding-left:25px"|Selecting a an Appropriate Text Editor|There are a wide range of '''Geany''' (recommended text editor for labs)<br>A simple graphical text editors editor for the python language and just about any of them will dodevelopers. As long as you get basic syntax highlighting and automatic indenting out of It is available in the application you are good to go. This section will go over a number of different text editors, showing off a few different text editors so students may find their favourite. There are no wrong answers here, give them all a try and use your favouriteCentOS package repositories.<br><blockquote>'''Vim'''<br>As a system administrator you have probably spent a ton of time inside vim. Well vim is just as a powerful text editor for system administration and useful when you get to programming, all tasks. All of the shortcuts and commands you've learned over the years will help you edit programs efficiently. On top of what you already know, it might be time to customize vim a little more for programming. Vim can actually be modified to become a full programming environment with all the features you you'd expect.</blockquote><blockquotebr>'''AtomSublime'''<br>"A hackable Another powerful and popular text editor designed for the 21st Century". This text editor is a powerful tools that comes with everything your need right out of the box. Atom allows for deep customization from everything from complete functionality changes to just changing the themeprogramming. Definitely worth checking out, especially for python developmentIs not free or open source.</blockquote><blockquote>'''Sublime'''<br>Insert discussion here</blockquote>}}</blockquote></blockquote>
<ol><li value=6" style="margin-left:25px;">Installing vim(Vi IMproved) will give us syntax highlighting and allow for advanced customization for terminal editing:<source>yum install vim-common vim-enhanced # Install vim </source></li><li style="margin-left:25px;"> '''Python pip ''' is a package manager specifically for Python. While it is usually not recommended to install software outside of '''dnf ''' or '''yum''', sometimes the only way to get a specific or latest version will be through pip:<sourcelang="bash">
yum install python-pip # Install python2.7 pip
yum install python34-pip # Install python3.4 pip
</source></li>
<li style="margin-left:25px;">Upgrade python34-pip with the following command:<source lang="bash">pip3.4 install --upgrade pip</source></li><li style="margin-left:25px;">Issue the following command to install '''git''':<sourcelang="bash">
yum install git # Install git command line tool
</source></li></ol>
<blockquote><blockquotestyle="margin-left:35px;">{{Admon/tip|What is a Git?|In the dictionary, "git" is defined as an unpleasant or contemptible person. In the IT industry on the other hand, '''Git''' refers to a '''version control system ''' that allows you to track any changes made to files and programs. The benefit to using Our primary use for git is primarily found when it's used with multiple people, sharing and working on code together. While that is not how we will be using it in this course, you may find some benefits in using it for managing multiple versions of the same program or will be for backing up your code backup onto to the internet. Check out '''bitbucket ''' for a free private code repository.}}</blockquote></blockquote>
<ol><li value="98" style="margin-left:25px;">IPython will be one of the tools we will use the most. Lets install it. You will learn more about it in the next section:<sourcelang="bash">
yum install python-ipython # Install ipython for python2.7
pip3.4 install ipython # Install ipython for python3.4
</source></li>
<li style="margin-left:25px;">Issue Exit from the superuser shell to your regular user shell and issue the following commands in your Ipython shell to check your work for this section:<sourcelang="bash">mkdir -p ~/ops435/lab1/
cd ~/ops435/lab1/
pwd #confirm that you are in the right directory
ls CheckLab1.py || wget matrixhttps://raw.senecacollegegithubusercontent.cacom/~acoatleySeneca-willisCDOT/ops435/master/LabCheckScripts/CheckLab1.pypython python3 ./CheckLab1.py -f -v lab0apython3 ./CheckLab1.py -f -v lab0b
</source></li>
<li style="margin-left:25px;">Before moving on to the next step, make sure you identify and correct any and all errors in "lab1a.pylab0b"output. When the check script tells you everything is "ok", you may proceed to the next step.</li></ol> == Part 3 - Lab Check lab0c == <prebr>cd ~/ops435/lab1/pwd #confirm that you are in the right directoryls CheckLab1.py || wget matrix.senecacollege.ca/~acoatley-willis/CheckLab1.pypython ./CheckLab1.py -f -v lab0c</prebrBefore moving on to the next step make sure you identify any and all errors in "lab1a.py". When the check script tells you everything is "ok", you may procede to the next step.
= INVESTIGATION 2: USING THE "IPYTHON COMMAND LINE INTERFACE " CLI =
:'''IPython ''' is an interactive environment that allows us to run python code line by line as we write it. This will function almost exactly also act like a bash shell prompt, allowing users to enter a command and recieve the output backlimited number of Bash shell commands. However the You will notice this by seeing an [IN] prompt where to enter commands and an [OUT] prompt that we will be running are lines of python codedisplay output from issued commands. Using this method we We will start creating scripts out of the code we build within this '''IPython''' environment.<blockquote style="margin-left:35px;">{{Admon/important|style="padding-left:25px"|ipython and python|[https://plot.ly/python/ipython-vs-python/ What is the difference between '''python''' and '''ipython'''?] Please note that in later labs, you can use either '''python''' or '''ipythone''' as the IPython environmentinteractive python shell.}}</blockquote>
=== Part PART 1 - Common IPython Ipython Commands and Features ===
==== Using Magic Functions ====
:Lets start with trying to run begin by running some python code in a the ipython interactive shell. This is a advanced python shell, similar to the bash shell that you have been using throughout the linux Linux courses. Throughout these labs the term command can also refer to these "magical functions".
:'''Perform the following steps:'''
:#Make sure you're using your regular user login and not using the root user for the following section.:#To get into access the '''ipython ''' shell type, issue the following command:<source>
ipython3
</source>Now we are now inside the IPython environment. We can run some basic bash commands in here, within this is done through shell by using issuing IPython magic functions. <br>:#Lets try a few commands out now:<source>% ls% pwd% cd ~/% ls</source>Now hold on. '''Remember:''' You are not using Python here. These , instead, these are aliases, for Bash shell commands that IPython gives you access to. What you are actually using is bash, but not all bash commands are available in the IPython environment.<br><br>:#Lets find out which ones are available, type the following command into the IPython shell:<source>% alias</source>We should now have a list of all the bash commands available in IPython. Shortly we will go over how to add new bash commands into this environment, but you must remember, these are only here to assist in your python scripting, we are not here to learn bash commands.<br><br>:#Next lets add Lets setup a new bash command that seems directory structures for completing and organizing labs. These should be the locations to be missing from this list:store your lab scripts.<source>%alias vim vim mkdir ~/ops435/lab2 mkdir ~/ops435/lab3 mkdir ~/ops435/lab4 mkdir ~/ops435/lab5 mkdir ~/ops435/lab6 mkdir ~/ops435/lab7 mkdir ~/ops435/lab8
</source>
#The vim command will give us our much needed syntax highlighting, while we are editing scripts from within the IPython environment. These magic %alias functions do not save in between sessions, this creates a problem since you would have to create them every time you start IPython. This will create a error:<source>exitipython3%vim</source>You should be seeing an error telling you invalid syntax. This is happening because we need to create a config file to make this alias persist in-between sessions.<br><br>#Exit your current IPython session:<source>exit</source>#Now, create a new file and add the following content to it:<source>vim ~/.ipython/profile_default/startup/00-alias.ipy </source>#Place our alias inside:<source>%alias vim vim</source>#Save and quit the file. Now lets return to our IPython shell and confirm that our alias is available right away:<source>ipython3%vim</source>At this point vim should open successfully and you should now understand how to create new IPython aliases and store them persistently. Use these aliases to customize your environment with any bash commands you thing IPython is missing. Exit vim now and head back to the IPython shell. <br><br>#Lets setup a directory structures for completing and organizing labs. These should be the locations to store your lab scripts.<source>%mkdir ~/ops435%mkdir ~/ops435/lab1%mkdir ~/ops435/lab2%mkdir ~/ops435/lab3%mkdir ~/ops435/lab4%mkdir ~/ops435/lab5%mkdir ~/ops435/lab6%mkdir ~/ops435/lab7%mkdir ~/ops435/lab8</source>#If you are interested in finding more information about other magic functions in IPython, try entering then within the IPython shell , and typing enter the following(press the letter '''q''' to exit this function):<source>% magic
</source>
:::This should show you resource will appear OVERWHELMING (a OVERWHELMING huge amount of information, as )! As we move through the throughout this course we , you will slowly use different magic functions from here, but we will never use all of them. To be continued. Magic functions than just running bash commands. They cover a huge range of different tasks, while we are writing code, allowing us to interactively inspect the Python we are writing and running. Lets move on for now. == Part 1 - Lab Check lab1a ==
<ol><li value="6" style="margin-left:25px;">Issue the following command to exit your ipython session:<source>
exit
</source>
</li>
:In the future see if '''ctrl-d''' works instead of issuing the exit command to quit the ipython shell.
</li>
Running <li style="margin-left:25px;">Perform the following steps to evaluate this check script will give you an error, read this error message to see if you can figure out why. This is happening because we are checking a lab script file that we HAVE NOT created yet, so these errors are ok for nowunit. But run Run these check scripts regularly as you work through the labs, they may give you hints if you get stuck. </li> :<presource lang="bash">
cd ~/ops435/lab1/
pwd #confirm that you are in the right directory
ls CheckLab1.py || wget matrixhttps://raw.senecacollegegithubusercontent.cacom/~acoatleySeneca-willisCDOT/ops435/master/LabCheckScripts/CheckLab1.pypython python3 ./CheckLab1.py -f -v lab1alab0c</presource></ol><br><br>
Proceed to the next section, and run the check script when you have finished.= INVESTIGATION 3: WRITING PYTHON SCRIPTS =
= INVESTIGATION 3: WRITING A PYTHON SCRIPT =In this investigation we will start writing our very first python scripts. These will be very basic and help us practice syntax and foundation skills, such as: outputting text to the screen, storing data inside objects, and using math operators.
During this investigation we will start writing our very first python scripts. These will be very basic <blockquote style="margin-left:35px;">{{Admon/important|style="padding-left:25px"|Object and help us practice syntax Variable|The terms '''object''' and foundational skills, such as: outputing text '''variable''' are used to refer to a data item in computer programming. The term '''variable''' are mostly used in 3rd generation programming/scripting languages (e.g. bash) while the screenterm '''object''' is preferred in object oriented programming/scripting languages like Python. In the context of Python programming/scripting, storing data inside variablesWhen you see the term '''variable''' in the lab instructions, and using math operatorsit can be replaced by the term '''object'''.}}</blockquote>
=== Part 1 - Printing ===
Lets start IPython interpreter and start writing some python code.=== PART 1 - Common Introductory Python Functions ===
<pre>ipython3%cd ~/ops435/lab1%pwd%ls</pre>====Creating the introductory "Hello World" Script====
Our first You will learn to create a simple python script in this section. This python code we script will write is just print the print functiontext "hello world". A function The "hello world" an old traditional first program students usually are taught to create, which is code that has been defined in another location. Functions can take arguments, use these arguments in some waybased on the first programming example from the first C programming text co-written by Dennis Ritchie, the creator of the C programming language and then usually return a resultBrian Kernighan. The first function we You will use is learn how to run the python script in the "print()" functions, it's sole purpose is to output information python3 shell as well as learn how to run the python script from the screenbash shell.
<pre>print()</pre>:'''Perform the following steps:'''
You will notice that nothing happened when we ran this "print()" function. This is because we didn't pass any arguments to it, lets try again.
:#Create a new python file in your ~/ops435/lab1 directory. Call it lab1a.py. The first Python code we will write is going to call the print function. A function is code that has been defined in another location. Functions can take arguments, use these arguments in some way, and then usually return a result. The first function we will use is the "print()" functions, it's sole purpose is to output information to the screen.<prebr><br>:#Add the following line into your source code file:<source>print()</source>And run it from the command-line: <source>python3 ./lab1a.py</source>You will notice that nothing is printed even though we called the "print()" function. This is because we didn't pass any arguments to it, lets try again.<br><br>:# Modify your call to print() to inlcude an argument ('hello world'):<br><source>
print('hello world')
</presource> This time we should now see that the python function "print()" has outputted to the screen the words 'hello world'. In python a word or a bunch of characters like 'hello world' is called a 'string'. So what we did In the above isexample, passed a '''string''' was passed as a '''argument''' to the print '''function'''. These words are important for understanding and talking about different aspects of code.<br><br>  === Part 2 - Hello World === Next, we will make our first script with :# Note that there are similarities between the above Python print() function. Open and the Bash echo command, but Python is more picky than bash (which is a new text file called "lab1agood thing).py"Try to run print without the brackets or without the quotes to see what happens. <preblockquote style="margin-left:35px;">%vim ~{{Admon/ops435/lab1/lab1atip|Reading errors|One of the things that makes a good programmer is debugging skills. The first and most important debugging technique is reading and understanding error messages. Try to understand what the errors are saying even if you think you already know what the problem is and already have some idea about how to fix it.py}}</preblockquote>  <ol><li value="5" style="margin-left:25px;">Write the following code into our python file. Note the she-bang line at the top of the file to run this script in the python3 environment. You will need to add this she-bang line for all python scripts you create for this course.<presource lang="python">
#!/usr/bin/env python3
print('Hello world')
</presource><li style="margin-left:25px;">Another way of running a pythion program is executing it directly, e.g.: <source>./test.py</source>Note that the file will need execute permissions even though you ran it just fine earlier. Why is that? <li style="margin-left:25px;">Download the check script and check your work. Enter the following commands from the bash shell.<source lang="bash"> cd ~/ops435/lab1/ pwd #confirm that you are in the right directory ls lab1a.py #confirm that you have the lab1a.py script in your directory ls CheckLab1.py || wget https://raw.githubusercontent.com/Seneca-CDOT/ops435/master/LabCheckScripts/CheckLab1.py python3 ./CheckLab1.py -f -v lab1a</source><li style="margin-left:25px;">Before moving on to the next step make sure you identify any and all errors in "lab1a.py". When the check script tells you everything is "ok", you may proceed to the next step.</ol>
Save the file and quit vim. We will now go over the process of manually running this python script. Both in the Bash shell and in the IPython shell.=== PART 2 - Working with Python Objects ===
:In Python, an object is used to store data for use later in the program. This data can be a string, integer, decimal number, characters, etc. We will only be covering '''string''' and '''integer''' variables in this lab. You will learn and use other python object types in future labs.
Now lets try running the script directly from the IPython shell.==== String Objects ====
<pre>ipython3%run ~/ops435/lab1/lab1a:String objects contain text to be used in your program. Examples of strings could be user-names, full-names, item descriptions, etc. We will now demonstrate to assign a string to an object and how to display contents stored in a string object.py</pre>
Your python script should have run, if you have any errors you should check that you typed :'''Perform the script in exactly. Be careful of extra spaces, symbols, letters, or lowercase/uppercase differences. following steps:'''
Exit out of IPython. Now from the Bash shell we will give it the correct linux permissions and run it. This is just showing the multiple ways you can use this :#Create a python script. You are not required to have IPython running on a system, however hopefully we can use IPython's powerful features to our advantage. <pre>exit</pre> <pre>chmod 755 ~/ops435/lab1/lab1a.pypython3 ~/ops435/lab1/lab1a(called lab1b.py</pre> === Part 2 - Lab Check lab1a === This course is designed with a unit testing suite, which can be used to look at the scripts you write ) and give realfirst -time feedback. This feedback is not perfect, however it may offer some hints if you get stuck start with a error. It can also be used few simple things to make sure you are on the write track, and show progress. Download the check script. Enter the following commands from the bash shell.try: <pre>cd ~/ops435/lab1/pwd :#confirm that you are in the right directoryls lab1a.py #confirm that you have the lab1a.py script in your directoryls CheckLab1.py || wget matrix.senecacollege.ca/~acoatley-willis/CheckLab1.pypython ./CheckLab1.py -f -v lab1a</pre> Before moving on to the next step make sure you identify any and all errors in "lab1a.py". When the check script tells you everything is "ok", you may proceed to the next step. === Part 3 - Variables === A variable is used to store data for use later in the program. This data can be a string, integer, decimal, etc. ==== Part 3 - strings ==== First Let's make a new variable object containing a value. :<presource lang="python">name = 'Thomas'</presourceInspect the value. <pre>name</pre> :#Print the value to the screen. :<presource lang="python">
print(name)
</presource>:#Think about why this does something different:<source lang="python">print('name')</source>:#Now lets try something new, we are going to print out the string and concatenate/combine it with another string. The plus sign can be used to join 2 strings together. However, make sure that your variable object is always outside the quotes, or it will not resolve to a value. <presource lang="python">
print('I have a friend named ' + name)
</presource=== Part 3 - Evaluation === Create a :#To gain practice, complete your python scriptwith the following content and details: lab1b.py::::* The script should have a '''Shebang line''' like you did for your lab1a.py python script::::* The script should use a single variable object called "name"::::* The value of the "name" variable object should be "Isaac"::::* The script, when executed, should print out "How old are you Isaac?" Example ::::*Sample run: <presource>% cd ~/ops435/lab1/%run ./lab1b.py How old are you Isaac?</presource> Try the check checking script as you are working through a script to sometimes get hints.<br><br> <ol><li value="7" style== Part 3 "margin- Lab Check lab1b === This course is designed with a unit testing suite, which can be used to look at the scripts you write left:25px;">Download and give real-time feedback. This feedback is not perfect, however it may offer some hints if you get stuck with a error. It can also be used to make sure you are on run the write track, and show progress. Download the check checking script. Enter the following commands from the '''bash shell.''':<presource lang="bash">
cd ~/ops435/lab1/
pwd #confirm that you are in the right directory
ls CheckLab1.py || wget matrixhttps://raw.senecacollegegithubusercontent.cacom/~acoatleySeneca-willisCDOT/ops435/master/LabCheckScripts/CheckLab1.pypython python3 ./CheckLab1.py -f -v lab1b</presource></li><li style="margin-left:25px;"> Before proceeding, make certain that you identify any and all errors in "lab1b.py". When the check script tells you everything is "ok", you may proceed to the next step.</li></ol>
Before moving on to the next step make sure you identify any and all errors in "lab1a.py". When the check script tells you everything is "ok", you may procede to the next step.==== Integer Objects====
=== Part 4 :In Python, integer objects are used to store an integer numbers that can be used for mathematical operations (discussed in the next section). Integers do NOT contain decimals, and they can be signed (+ or - Integers ===) or unsigned. Here we will store integers in a object, perform math operations, and display the results.
Lets enter into IPython to test out variables.<pre>ipython3</pre>:'''Perform the following steps:'''
:#Create a python script (called lab1c.py) and first - start with a few simple things to try: :#Lets create some new variables objects to play with.<presource lang="python">
num1 = 5
num2 = 10
</presourceIn IPython we :#You can inspect these variables by just typing the name of print the variable. But values in a those integer objects:<source lang="python script this will not provide any output. This feature is useful however for debugging. <pre">print(num1)print(num2)</presource:#Now we will make a new variable integer object and try some math. :<presource lang="python">
sum = num1 + num2
</presource> This will add the values contained in the variables integer objects together, providing a sum. However you will note that there is no output. First lets Let's inspect the new value. :<pre>sum</pre> Does this value look right? If we wanted to print this out to the screen we could use the following source lang="python code. <pre">
print(sum)
</presource>Does this value look right? Are you sure?<br:#Now lets try printing this sum out with a string.:<presource lang="python">
print('The sum is: ' + sum)
</presource> What happened? Did you receive an error? This will may have been the first time you've seen this error, but it won't be the last. What we tried to do is combine a string with a number, and this won't work.  <br><br>In order to use display this number as a string we will use the "str()" function on it. The "str()" function will return a string of your number and provide it as a argument to "print()". This function will not change the value of your variableobject, your variable object is still a an intergerobject.<br><br> :# Issue the following:<presource lang="python">
print('The sum is: ' + str(sum))
</presource>What did you notice this time?<br /=== Part 4 - Evaluation === Create a :#To gain practice, complete your python scriptwith the following features: lab1c.py:::* The script should have a Shebang line.:::* The script should have a variable an object called '''name''':::* The script should have a variable an object called '''age''':::* The value of the '''name''' variable object should be '''Isaac''':::* The variable object '''age''' should contain a integer:::* The value of the '''age''' variable object should be '''72''':::* The script, when executed, should print out "Isaac is 72 years old!" :::Example run: <presource>%cd ~/ops435/lab1/%run ./lab1c.py
Isaac is 72 years old!
</presource><br>Try the check script as you are working through a script to sometimes get hints.<br><ol><li value=10" style="margin-left:25px;">Download and run the checking script. Enter the following commands from the bash shell:<source lang="bash">cd ~/ops435/lab1/pwd #confirm that you are in the right directoryls CheckLab1.py || wget https://raw.githubusercontent.com/Seneca-CDOT/ops435/master/LabCheckScripts/CheckLab1.pypython3 ./CheckLab1.py -f -v lab1c</source></li><li style="margin-left:25px;">Before moving on to the next step make sure you identify any and all errors in "lab1c.py". When the check script tells you everything is "ok", you may proceed to the next step.</li></ol>
Try the check script as you are working through a script to sometimes get hints.=== PART 5 - MATH OPERATORS ===
==== Part 4 - Lab Check lab1c ====:In the previous section, you performed a couple of simple mathematical operations. In this section, you will learn some additional mathematical operations.
This course is designed with a unit testing suite, which can be used to look at :'''Perform the scripts you write and give real-time feedback. This feedback is not perfect, however it may offer some hints if you get stuck with a error. It can also be used to make sure you are on the write track, and show progress.following steps:'''
:# Try some of the following to see what happens in Python:<source lang="python">print(10 + 5) # additionprint(10 - 5) # subtractionprint(10 * 5) # multiplicationprint(10 / 5) # divisionprint(10 ** 5) # exponents</source>NOTE: You must be careful when combining more complex math operators together. Python uses '''PEMDAS''' ('''P'''arentheses, '''E'''xponents, '''M'''ultiplication and '''D'''ivision, '''A'''ddition and '''S'''ubtraction) to resolve math.<br><br>:# Go over the below examples and see if you understand each situation:<source lang="python">print(10 + 5 * 2) # multiplication happens before additionprint((10 + 5) * 2) # parentheses happen before multiplicationprint(10 + 5 * 2 - 10 ** 2) # first exponents, then multiplication, then addition and subtraction from left-to-rightprint(15 / 3 * 4) # division and multiplication happen from left-to-rightprint(100 / ((5 + 5) * 2)) # the inner most parentheses are first performing addition, then parentheses again with multiplication, finally the division </source>:#To gain practice, complete your script with the following content and details:::* The script should have a Shebang line.::* The object '''x''' should contain a integer with the value '''10'''::* The object '''y''' should contain a integer with the value '''2'''::* The object '''z''' should contain a integer with the value '''5'''::* The script, when executed, should print out "10 + 2 * 5 = 20" (the printout should change if the values in the objects change):::Example run: <source>cd ~/ops435/lab1/./lab1d.py10 + 2 * 5 = 20</source>Try the checking script as you are working through a script to sometimes get hints.<br><br><ol><li style="margin-left:25px;" value="4">Download and run the check checking script. Enter the following commands from the bash shell.:<presource lang="bash">
cd ~/ops435/lab1/
pwd #confirm that you are in the right directory
ls CheckLab1.py || wget matrixhttps://raw.senecacollegegithubusercontent.cacom/~acoatleySeneca-willisCDOT/ops435/master/LabCheckScripts/CheckLab1.pypython python3 ./CheckLab1.py -f -v lab1clab1d</presource> Before moving on to the next step make sure you identify any and all errors in "lab1alab1d.py". <br><br></li><li style="margin-left:25px;">When the check script tells you everything is "ok", you may procede proceed to the next step.  === Part 5 - Math Operators === Python has a number of math operators you can use in your programs.<prebr><br>10 + 5 # addition10 - 5 # subtraction10 * 5 # multiplication10 </ 5 # division10 ** 5 # exponentsli></preolBut you must be careful when combining more complex math operators together. Python uses PEMDAS(Parentheses, Exponents, Multiplication and Division, Addition and Subtraction) to resolve math. Go over the below examples and see if you understand each situation. <prebr>10 + 5 * 2 # multiplication happens before addition(10 + 5) * 2 # parentheses happen before multiplication10 + 5 * 2 - 10 ** 2 # first exponents, then multiplication, then addition and subtraction from left-to-right15 / 3 * 4 # division and multiplication happen from left-to-right100 / ((5 + 5) * 2) # the inner most parentheses are first performing addition, then parentheses again with multiplication, finally the division </prebr>
= LAB 1 SIGN-OFF (SHOW INSTRUCTOR) =
[[Image:lab1_signoff.png|thumb|right|450px|Students should be prepared with '''all required commands (system information) displayed in a terminal (or multiple terminals) prior to calling the instructor for signoff'''.]]
===Part 5 - Evaluation ===
Create a python script: lab1d.py* The script should have a Shebang line.* The variable '''x''' should contain a integer with the value '''10'''* The variable '''y''' should contain a integer with the value '''2'''* The variable '''z''' should contain a integer with the value '''5Have Ready to Show Your Instructor:'''* The script, when executed, should print out "10 + 2 * 5 = 20"
Example run: :<prespan style="color:green;font-size:1.5em;">%cd ~&#x2713;</ops435span> Output of: <code>./lab1CheckLab1.py -f -v</code>%run ::<span style="color:green;font-size:1.5em;">&#x2713;</span> Output of: <code>cat lab1a.py lab1b.py lab1c.py lab1d.py10 + 2 * 5 = 20</precode>
Try :'''Be able to answer any questions about the check script as lab to show that you are working through a script to sometimes get hints.understood it!'''<br>:'''For sections A & B:'''
::<span style=== Part 5 color:green;font- Lab Check lab1d ===size:1.5em;">&#x2713;</span> Submit your output and Python scrips via Blackboard instead.
This course is designed with a unit testing suite, which can be used to look at the scripts you write and give real-time feedback. This feedback is not perfect, however it may offer some hints if you get stuck with a error. It can also be used to make sure you are on the write track, and show progress.= LAB REVIEW =
Download :# Write the command to change the check scripthostname of your Linux machine to '''centos7'''. Enter :# What is the following commands from purpose of '''git'''? How will git be used in our OPS435 course?:# Write the command to create an '''alias''' for the Linux command vim which will be called vi in your ipython3 session.:# Write the absolute pathname for the bash shellipython3 alias configuration file.:# Write Python code that when run, will perform the following tasks:<ol type="a"><li>Contain a she-bang line</li><li>Display a greetings message to the user</li><preli>cd ~display an empty line ('''hint:''' use the special character '''\n''' to print the a new-line character)</li><li>Display text, '''"Your current directory is:"''' (You are NOT required to display quotation marks)</li><li>Display the current working directory pathname (using an appropriate command)</li><li>Display another empty line</ops435li></lab1ol>:# How do you execute a Python script when you are within the <u>ipython3</u> shell?pwd :#confirm that How do you execute a Python script when you are in the right directory<u>Bash</u> Shell (i.e. NOT within the Ipython3 shell)?ls :# Write the pipeline command to check if the CheckLab1.py || wget matrixchecking script exists, and download it from the location:<br>https://raw.senecacollegegithubusercontent.cacom/~acoatleySeneca-willisCDOT/ops435/master/CheckLab1.pypython .LabCheckScripts/CheckLab1.py -f -v lab1d</pre>
Before moving on to the next step make sure you identify any and all errors in "lab1a.py". When the check script tells you everything is "ok", you may procede to the next step.[[Category:OPS435-Python]]

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