Changes

= Lab Preparation LAB OBJECTIVES =

Selecting:After selecting an appropriate text editor to use, installingthen you will start to create '''Python''' scripts to learn basic operations such as: '''printing text''', '''using objects''', and setting up your Linux Distribution environment. Learning basics of interacting with pythonperforming '''math operations'''.<br><br>

= INVESTIGATION 1: INSTALLING LINUXVM=

=== Part PART 1 - Installing Your Linux Distribution ===

Since Python runs independently regardless : Most of you will likely use the of school's Windows machines with the Linux distributionVmware hypervisor. It is also possible to use your own computer, but check with your professor before you have some flexibility of which Linux OS to usedo 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. Below It is a table displaying the characteristics of the recommended that students note general improvements/differences in Python2 and Python3.  :'''<u>Centos vs Fedora distributions and related Python packages7 VM Details / Minimum Requirements:</u>''' ::*'''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

:'''Perform the following steps:'''

:#To keep everything simple we are going to use Centos7 Regardless of the Linux distribution that is used for each this course, these lab, install will be using and referring to the latest graphical current version of that '''CentOS 7''' (Graphical Desktop) for our main Linux OSmachine. 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.<brblockquote style="margin-left:35px;"><br>This course {{Admon/important|style="padding-left:25px"|Unit Feedback Scripts|Each '''Part''' (within an 'Investigation) is designed with referred to as a '''Unit'''. Each Unit will require that the student download and run a unit testing suite'''Unit Feedback Script''', which can be used to look at provides the scripts you write and give OPS435 student "real-time feedback" of their completed work.<br>This feedback is not considered to be perfector fool-proof; however, however it may offer some provide feedback (hints if you get ) in case a student gets stuck with a or experiences an errorwhen performing administration tasks or when creating their Python scripts. It These unit feedback scripts can also be used to make sure you are confirm that the student's Python script is on the right track, and show provide a consistent record of their Python scripting progressthroughout their labs.}}<br/blockquote> <!--<ol><brli value="3" style="margin-left:25px;">#Download the check script. Enter Issue the following commands from (as a regular user) in order to setup, download and run the bash shell.first unit feedback script:<br><sourcelang="bash">

pwd # <-- i.e. confirm that you are in the right correct directoryls CheckLab1.py || wget matrixhttps://raw.senecacollegegithubusercontent.cacom/~acoatleySeneca-willisCDOT/ops435/master/LabCheckScripts/CheckLab1.pypython python3 ./CheckLab1.py -f -v lab0a</source></li>#<li 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></ol>-->

=== Part PART 2 - Setting Up up Your Linux Python Environment For OPS435 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">

:#Install extra packages for enterprise linux:<sourcelang="bash">

:#Next install applications that we needrequired, first Python version 3 and version 2:<sourcelang="bash">

:#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">

:# 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">

#Installing vim(Vi IMproved) ::You will give us syntax highlighting 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 allow productive during your Python coding sessions. ::Below is a listing of several common text editors and their features.<blockquote style="margin-left:35px;">{{Admon/tip|style="padding-left:25px"|Selecting an Appropriate Text Editor|'''Geany''' (recommended text editor for advanced customization labs)<br>A simple graphical text editor for terminal editing:developers. It is available in the CentOS package repositories.<sourcebr>yum install vim-common vim-enhanced # Install '''Vim'''<br>vim is a powerful text editor for system administration and programming tasks. All of the shortcuts and commands you've learned over the years will help you edit programs efficiently.<br>'''Sublime'''<br>Another powerful and popular text editor designed for programming. Is not free or open source.}}</sourceblockquote>#<ol><li value=6" 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">

</source><br/li>In the dictionary, <li style="gitmargin-left:25px;" 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 git is primarily found when it's used >Upgrade python34-pip 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 for backing up your code onto the internet. Check out bitbucket for a free private code repositoryfollowing command:<source lang="bash">pip3.4 install --upgrade pip<br/source><br/li>#<li style="margin-left:25px;">Issue the following command to install '''git''':<sourcelang="bash">

</source></li></ol>#<blockquote style="margin-left:35px;">{{Admon/tip|What is a Git?| '''Git''' refers to a '''version control system''' that allows you to track any changes made to files and programs. Our primary use for git in this course will be for backup onto to the internet. Check out '''bitbucket''' for a free private code repository.}}</blockquote> <ol><li value="8" 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">

</source>#Issue the following commands in your Ipython shell to check your work for this section:<source/li>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 lab0b</source>#Before moving on to the next step, make sure you identify and correct any and all errors in li style="lab1a.pymargin-left:25px;". When >Exit from the check script tells you everything is "ok", you may proceed superuser shell to the next step. === Part 3 - Selecting a Text Editor to Use For Your OPS435 Labs === There are a wide range of text editors for the python language and just about any of them will do. As long as you get basic syntax highlighting and automatic indenting out of 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 favourite.  <table border="1" cellspacing="0" cellpadding="5" width="40%" ><tr><td width="150px">'''Text Editor'''</td><td>'''Characteristics'''</td></tr> <tr><td valign="top">'''Vim'''</td><td valign="top">As a system administrator you have probably spent a ton of time inside vim. Well vim is just as powerful regular user shell and useful when you get to programming, all issue the shortcuts and following 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 yould expect.</td></tr><tr><td valign="top">'''Atom'''</td><td valign="top">"A hackable text editor for the 21st Century". This text editor is a powerful tools that comes with everything check your need right out of the box. Atom allows work for deep customization from everything from complete functionality changes to just changing the theme. Definitely worth checking out, especially for python development.this section:</td></tr> <tr><td valignsource lang="topbash">'''Sublime'''</td><td valign="top">Sublime is a popular text editor with tons of customizations and themes.</td></tr><tr><td valign="top">'''Other Editors'''<mkdir -p ~/td><td valign="top">x<ops435/td></tr><lab1/table> == Part 3 - Lab Check lab0c == <pre>

ls CheckLab1.py || wget matrixhttps://raw.senecacollegegithubusercontent.cacom/~acoatleySeneca-willisCDOT/ops435/master/LabCheckScripts/CheckLab1.pypython python3 ./CheckLab1.py -f -v lab0clab0apython3 ./CheckLab1.py -f -v lab0b</presource></li><li style="margin-left:25px;">Before moving on to the next step, make sure you identify and correct any and all errors in "lab0b" output. When the check script tells you everything is "ok", you may proceed to the next step.</li></ol><br><br>

Before moving on to the next step make sure you identify any and all errors in = INVESTIGATION 2: USING THE "lab1a.pyIPYTHON". When the check script tells you everything is "ok", you may procede to the next step.CLI =

:'''IPython''' is an interactive environment that allows us to run python code line by line as we write it. This will also act like a bash shell prompt allowing users to enter a limited number of Bash shell commands. You will notice this by seeing an [IN] prompt where to enter commands and an [OUT] prompt that will display output from issued commands. We will start creating scripts out of the code within this '''IPython''' environment.<blockquote style= INVESTIGATION 2"margin-left: USING THE IPYTHON COMMAND LINE INTERFACE 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 interactive python shell.}}</blockquote>

 === Part PART 1 - Common IPython Ipython Commands and Features ===

: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".

:#Make sure you'''Perform re using your regular user login and not using the root user for the following stepssection.:#To access the ''' #To get into the ipython ''' shell type, issue the following command:<source>

</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

#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. 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

:::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.

<ol><li value="6" style= Part 1 "margin- Lab Check lab1a ==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>

<preli style="margin-left:25px;">Perform the following steps to evaluate this unit. Run these check scripts regularly as you work through the labs, they may give you hints if you get stuck.</li>:<source lang="bash">

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>

= 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>

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.

:#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>

</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">

</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>

<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'</presource> Inspect the value. <pre>name</pre> :#Print the value to the screen. :<presource lang="python">

</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">

</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">

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>

=== 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.

:#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">

</presource> In 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">

</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">

</presource>Does this value look right? Are you sure?<br> :#Now lets try printing this sum out with a string.:<presource lang="python">

</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">

</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

</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>

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">

ls CheckLab1.py || wget matrixhttps://raw.senecacollegegithubusercontent.cacom/~acoatleySeneca-willisCDOT/ops435/master/LabCheckScripts/CheckLab1.pypython python3 ./CheckLab1.py -f -v lab1clab1d</source>Before moving on to the next step make sure you identify any and all errors in "lab1d.py".<br><br></li><li style="margin-left:25px;">When the check script tells you everything is "ok", you may proceed to the next step.<br><br></preli></ol><br><br>

Before moving on to the next step make sure you identify any and = LAB 1 SIGN-OFF (SHOW INSTRUCTOR) =[[Image:lab1_signoff.png|thumb|right|450px|Students should be prepared with '''all errors required commands (system information) displayed in "lab1a.py". When the check script tells you everything is "ok", you may procede a terminal (or multiple terminals) prior to calling the next stepinstructor for signoff'''.]]

Python has a number ::<span style="color:green;font-size:1.5em;">&#x2713;</span> Output of math operators you can use in your programs: <code>./CheckLab1.py -f -v<pre/code>10 + 5 # addition10 ::<span style="color:green;font- 5 size:1.5em;">&# subtraction10 * 5 # multiplication10 x2713;</ 5 # division10 ** 5 # exponentsspan> Output of: <code>cat lab1a.py lab1b.py lab1c.py lab1d.py</precode>

But you must be careful when combining more complex math operators together. Python uses PEMDAS(Parentheses, Exponents, Multiplication and Division, Addition and Subtraction) :'''Be able to resolve math. Go over answer any questions about the below examples and see if lab to show that you understand each situation.understood it!'''<br>:'''For sections A & B:'''

::<prespan style=color:green;font-size:1.5em;">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 x2713;</prespan>Submit your output and Python scrips via Blackboard instead.

===Part 5 - Evaluation === Create a python script: lab1d.py* The script should have a Shebang line.* The variable # Write the command to change the hostname of your Linux machine to '''xcentos7''' should contain a integer with .:# What is the value purpose of '''10git'''? How will git be used in our OPS435 course?* The variable :# Write the command to create an '''yalias''' should contain for the Linux command vim which will be called vi in your ipython3 session.:# Write the absolute pathname for the ipython3 alias configuration file.:# Write Python code that when run, will perform the following tasks:<ol type="a integer with "><li>Contain a she-bang line</li><li>Display a greetings message to the value user</li><li>display an empty line ('''2hint:'''* The variable use the special character '''z\n''' should contain to print the a integer with the value new-line character)</li><li>Display text, '''5"Your current directory is:"'''* The script, when executed, should print out "10 + 2 * 5 = 20" Example run: (You are NOT required to display quotation marks)</li><preli>%cd ~Display the current working directory pathname (using an appropriate command)</ops435li><li>Display another empty line</lab1/%run ./lab1d.py10 + 2 * 5 = 20li></preol> Try the check :# How do you execute a Python script as when you are working through a script to sometimes get hints.within the <u>ipython3</u> shell? === Part 5 - Lab Check lab1d === 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 :# How do you get stuck with execute a error. It can also be used to make sure Python script when you are on in the write track, and show progress<u>Bash</u> Shell (i.e.NOT within the Ipython3 shell)? Download :# Write the pipeline command to check if the CheckLab1.py checking script. Enter the following commands exists, and download it from the bash shell.location:<prebr>cd ~/ops435https:/lab1/pwd #confirm that you are in the right directoryls CheckLab1.py || wget matrixraw.senecacollegegithubusercontent.cacom/~acoatleySeneca-willisCDOT/ops435/master/CheckLab1.pypython .LabCheckScripts/CheckLab1.py -f -v lab1d</pre>