Final Review¶

Disclamer¶

This review is an attempt to highlight the major parts of the semester
Something being on this review does not garuntee it will be on the test
Something not being on this review does not mean it will not be on the test

Introduction¶

What is a scripting language
- How is it different than a compiled language
What are some common uses for scripting languages

Regular Expressions¶

What are they
- What are some uses of them?
What is the syntax?
- Character Class Symbols (\w, \W, etc.)
- Dot character .
- Quantifiers (?, *, +, {n}, {n,} , {n,m})
  - Greedy and non-greedy
- Anchors (^, $, \b, \B)

In [ ]:

%%perl
use feature qw(say);
$string = "a b c" ;
say $string if $string=~ /\w+/;

In [ ]:

%%perl
use feature qw(say);
$string = "abc" ;
say $string if $string=~ /\W+/;
$string = ",." ;
say $string if $string=~ /\W+/;

In [ ]:

%%perl
use feature qw(say);
$string = "abba" ;
say $string if $string=~ /^a.+a$/;
$string = "aa" ;
say $string if $string=~ /^a.+a$/;

Regular Expressions¶

Syntax Continued
- Grouping ()
- Capture References \1
- Pattern Modifiers i,g
- Custom Character classes []
- Alternation |

In [ ]:

%%perl
use feature qw(say);
$string = "abba" ;
say $string if $string =~ /(\w)(\w)\2\1/

In [ ]:

%%perl
use feature qw(say);
$string = "ABBA" ;
say $string if $string =~ /(a)(b)\2\1/i

In [ ]:

%%perl
use feature qw(say);
$string = "10 GB";
say $string if $string =~ /\d+ [GKMT]B/

In [ ]:

%%perl
use feature qw(say);
$string = "10 PB";
say $string if $string =~ /\d+ [^GKMT]B/

Regular Expressions¶

Subsitution
- Substitution in PERL s///
- Replacing Text
- Using Capture Buffers ($1 in replacement)
What is PCRE, how is this useful in other languages?

In [ ]:

%%perl
use feature qw(say);
$string = "Hello Class! Class!";
$string =~ s/Class!/World!/g;
say $string;

In [ ]:

%%perl
use feature qw(say);
$string = "410-455-1000";
$string =~ s/(\d\d\d)-(\d\d\d-\d\d\d\d)/($1) $2/;
say $string;

Shells¶

What is a shell?
What are some basic unix commands?
- What is the philosphy behind having so many commands?
Shell script basics
- Shebang line
- Comments
- Executing Them

In [ ]:

%%bash
cat to_sort1.txt
sort to_sort1.txt

In [ ]:

%%bash
head -n2 to_sort1.txt
tail -n2 to_sort1.txt

Shell Variables¶

Declaring Variables (no space between =)
- Arrays
Reference Variables
Interpolation
Command Line Arguments
Globbing

In [ ]:

%%bash
var=10
str="A String"
echo $var $str

In [ ]:

%%bash
arr=(10 20 30 40 50)
echo $arr ${arr[0]} 
echo ${arr[@]}

In [ ]:

%%bash
end="the end"
echo "I am interpolating ${end}ing."

Streams¶

Redirection
Pipes
Here Docs
Process Substitution <(command) Syntax

In [ ]:

%%bash
ls -lh *.ipynb > ls.txt
head ls.txt

In [ ]:

%%bash
ls *.ipynb | sort | head

Control Structures¶

If statements
- if then else fi
- Using [[ ]] or [ ]
- Basic tests (-eq, -ne,=,!=, etc.)
Switch Statement
- case pattern) ;; esac

In [ ]:

%%bash
a=10
if [[ $a -gt 5 ]]; then
    echo "YAY"
else
    echo "NAY"
fi

In [ ]:

%%bash
b="Hello"
case $b in
    *a)
        echo "Ends with an A"
        ;;
    He*)
        echo "Contains He"
        ;;
    *)
        echo "Default"
        ;;
esac

Looping¶

Count Style For Loops
- for ((x = S; x < N; x++)); do ... done
For-each style for f in *.html
- Brace Expansion

In [ ]:

%%bash
for ((x = 10; x < 20; x++)); do
    echo $x
done

In [ ]:

%%bash
for f in *2{0..9}.html; do
    wc -l "$f" 
done

Looping¶

While Loop
```
while CONDITION; do
#CODE_HERE
done
```

I/O¶

User input using read
Reading a file using read and while
echo and printf
Sourcing a file using .

In [ ]:

%%bash
while read line; do
    echo $line
done < to_sort1.txt

Math¶

(( )) Syntax
- Don't escape variables inside
$(( )) to save results
Can't do floating point without external program

In [ ]:

%%bash
x=0
#((x=0))
((x++))
echo $((x + 2))

Grep/Sed/Awk¶

What they are used for
Basic use of grep
- Using Perl style Regexes
- How to count number of matches

In [ ]:

%%bash
grep -Pc "\d\d\d-\d\d\d-\d\d\d\d" *.html | grep -P ":[^0]$"

Functions¶

Declaring Functions
- Accessing Function Parameters
Calling Functions
Scope
Returning from functions
- What does the return keyword actually do

In [ ]:

%%bash
function mystery(){
    diff $1 $2
    if [[ $? -ne 0 ]]; then
        echo "The files $1 and $2 are different"
    else
        echo "The files $1 and $2 are the same"
    fi
}

mystery "Lecture20.html" "Lecture20.html"

R¶

What it is used for
The assignment operator (<-)
Data types
- No Scalars
- List vs Vector
- Matrix vs DataFrame

In [ ]:

%%script R --no-save -q
a <- 4
print(a)

1D Structures¶

Creating a vector using c
Creating a list using list

In [ ]:

%%script R --no-save -q
vec <- c(1,2,3,4)
vec2 <- c(1,"2",3,4)
print(vec)
print(vec2)

In [ ]:

%%script R --no-save -q
l1 <- list(1,2,3,4)
l2 <- list(1,"2",3,4)
print(l1)
print(l2)

Matrices¶

Creating using matrix
Creating from vectors

In [ ]:

%%script R --no-save -q
m <- matrix(c(1,2,3,4,5,6),nrow=2)
print(m)

In [ ]:

%%script R --no-save -q
v2m <- c(1,2,3,4,5,6)
print(v2m)
dim(v2m) <- c(2,3)
print(v2m)

DataFrames¶

Creating from vectors
Reading in data
Common functions

In [ ]:

%%script R --no-save -q
df1 <- data.frame(int=c(1,2,3,4),float=c(1.01,2.0,3.0,4.0),str=c("One","Two","Three","Four"))
print(df1)

In [ ]:

%%script R --no-save -q
df2 <- read.csv("usm.csv")
print(df2)

Math in R¶

Can be on a high dimensional object

In [ ]:

%%script R --no-save -q
m <- matrix(c(1,2,3,4,5,6),nrow=2)
print(m + 5)

In [ ]:

%%script R --no-save -q
m <- matrix(c(1,2,3,4,5,6),nrow=2)
print(m * m)

Subsetting¶

Indexing starts at 1
Postive vs Negative Intenger Subsetting
Boolean Indexing
[] and [[]] operations
$ operator for Data Frames

In [ ]:

%%script R --no-save -q
v2 <- c('a','b','c','d')
print(v2[1])

In [ ]:

%%script R --no-save -q
v3 <- list('a','b','c','d')
print(v3[1])
print(v3[[1]])

In [ ]:

%%script R --no-save -q
v4 <- data.frame(letters=c('a','b','c','d'),numbers=c(1,2,3,4),symbols=c('!','#','$','@'))
print(v4$letters)

In [ ]:

%%script R --no-save -q
v5 <- c(1,2,3,4,5)
print(v5[-1])
print(v5[v5 %% 2 == 1])

Control Structures¶

If, else if
for ... in
- Rarely Seen in R
lapply

In [ ]:

%%script R --no-save -q
a <- 1
if(a > 0)
{
    print("This is Positive")
} else {
    print("This is Negative")
}

In [ ]:

%%script R --no-save -q
b <- c(1,2,3,4,5)
for(x in b){
    print(x)
}

Functions¶

How to declare
How to return from a function
How are defaul parameters evaluated?
Lazy Evaluation
Infix Functions
Assignment Functions

In [ ]:

%%script R --no-save -q
my_f <- function(a,def=1){
    print(def)
    a * a
}
print(my_f(10))
print(my_f(10,d=10))

In [ ]:

%%script R --no-save -q
`%+%` <- function(a,b){
    a * b
}
print(10 %+% 10)

In [ ]:

%%script R --no-save -q
`fir<-`<-function(x,value){
    x[1] <- value
    x
}
y <- c(1,2,3,5)
fir(y)<-10
print(y)

Objects¶

There are three systems
S3 basics
- Use of structure and class
- Constructors
Methods
- Generic Functions
- UseMethod
- Naming Conventions

In [ ]:

%%script R --no-save -q
per<-function(name,age){
    structure(list(m_name=name,m_age=age),class="per")
}

form<- function(ob){
    UseMethod("form")
}

form.per <- function(obj){
    paste(obj$m_name,"is",obj$m_age)
}

form.default <- function(obj){
    "Not a Person"
}

p <- per("Bob",20)
print(form(p))
print(form(10))

Regex Functions¶

grep vs grepl
perl=TRUE

In [ ]:

%%script R --no-save -q
print(grep("\\w\\w\\w",c("AABDF","AG","EOT"),perl=TRUE))
print(grepl("\\w\\w\\w",c("AABDF","AG","EOT"),perl=TRUE))

Web Basics¶

How does a HTTP Request Work?
- Headers, response
HTML
- What is it
- Not directly tested, in JS/PHP questions
CSS
- What is it
- Not directly tested, in JS/PHP questions

JavaScript¶

What is it?
- Where does it run?
- What can't it do?
Embedding JS in HTML
- <script> tag

<script src="location.js"></script>
<script src="https://example.com/remove_script.js"></script>
<script>
    //Embed Code
</script>

JavaScript¶

Declaring Variables
- Scope
Difference between == and ===

In [ ]:

%%html
<p id="results">To Be Replaced</p>
<script>
var abc = 1;
function scope_checker(){
   var abc = 2
}
scope_checker()
document.getElementById("results").innerHTML = abc;
</script>

In [ ]:

%%html
<p id="results1">To Be Replaced</p>
<script>
var abc = 1;
if(true){
   let abc = 2
}
document.getElementById("results1").innerHTML = abc;
</script>

In [ ]:

%%html
<p id="results2">To Be Replaced</p>
<script>
var s = "10"
var i = 10
if(s === i){
  document.getElementById("results2").innerHTML = "Triple Equal";  
}
else if(s == i){
      document.getElementById("results2").innerHTML = "Double Equal";
}
else{
    document.getElementById("results2").innerHTML = "Not Equal";
}

</script>

JavaScript¶

Arrays
- Are Objects
- Sorting
Strings
- Are objects
- Basic methods, concatenation

In [ ]:

%%html
<p id="results3">To Be Replaced</p>
<script>
var arr = new Array();
arr.push(1);
arr.push(2);
document.getElementById("results3").innerHTML = JSON.stringify(arr);
</script>

In [ ]:

%%html
<p id="results4">To Be Replaced</p>
<script>
var arr = [3,4,5];
document.getElementById("results4").innerHTML = JSON.stringify(arr);
</script>

In [ ]:

%%html
<p id="results5">To Be Replaced</p>
<script>
var arr = ["Sand","Dirt","Water"];
function s(a,b){
    a.charAt(a.length-3) - b.charAt(b.length-3);
}
document.getElementById("results5").innerHTML = JSON.stringify(arr.sort(s));
</script>

Control Structures in JS¶

if, else if, else
for, while
for .. in vs for .. of

In [ ]:

%%html
<p id="results8">To Be Replaced</p>
<script>
s = " ";
arr = [10,9,8,7,6,5];
for(i in arr){
    s += " " + i;
    i++;
}
document.getElementById("results8").innerHTML = JSON.stringify(s);
</script>

In [ ]:

%%html
<p id="results9">To Be Replaced</p>
<script>
s = " ";
arr = [10,9,8,7,6,5];
for(i of arr){
    s += " " + i;
    i++;
}
document.getElementById("results9").innerHTML = JSON.stringify(s);
</script>

Functions in JS¶

How to declare (the function keyword)
- Where they can be declared
How to pass functions to other functions
- Use in sort

In [ ]:

%%html
<p id="results10">To be Replaced</p>
<script>
do_something();
function do_something(){
    document.getElementById("results10").innerHTML = "Hoisted";
}
</script>

Objects in JavaScript¶

The this and new keywords
- How to make a "constructor" function
Dot syntax
- Methods are functions stored in keys
Generic { } syntax
Prototypes

In [ ]:

%%html
<p id="results11">To be Replaced</p>
<script>
function Course(department, number, section){
    this.department = department;
    this.number = number;
    this.section = section;
    this.print = function(){
        return "This is " + this.department + this.number + ",section "  + this.section;
    }
}

today = new Course("CMSC",433,"01");
document.getElementById("results11").innerHTML = today.print();
</script>

In [ ]:

%%html
<p id="results12">To be Replaced</p>
<script>
Vehicle = {go: function(){
        this.speed = 10;
}}

function Car(color){
    this.color = color;
    this.print = function(){
        return "The " +this.color + ' car is going ' + this.speed + " mph";
    }
}
Car.prototype = Vehicle;
vroom = new Car("red");
vroom.go();
document.getElementById("results12").innerHTML = vroom.print();
</script>

The DOM¶

What is the DOM (Document Object Model)
How to access from JS
Common properties of DOM objects
Common methods of DOM objects

In [ ]:

%%html
<p class="something"></p>
<div class="something"></div>
<script>
els = document.querySelectorAll(".something");
for(i = 0; i < els.length; i++){
    els[i].innerHTML = "Hello " + i;
}
</script>

Events¶

How are events used
How to bind events to an HTML element
- What is an event handler?
Some common events
- click
- load
- blur/focus

In [ ]:

%%html
<p id="event">To Respond</p>
<script>
document.getElementById("event").addEventListener('click',
                            function(e){
                                e.target.innerHTML = "Clicked"; 
                            });
</script>

In [ ]:

%%html
<input type="text" id="event2" />
<script>
document.getElementById("event2").addEventListener('focus',
                                                 function(e){
                                                    e.target.value = "In Focus"; 
                                                 });
document.getElementById("event2").addEventListener('blur',
                                                 function(e){
                                                    e.target.value = "Out of Focus"; 
                                                 });
</script>

AJAX¶

What did it originally stand for
What does it allow
How to make and handle a request
- open
- onreadystatechange
- send

In [ ]:

%%html
<p id="ajaxResult"></p>
<script>
    var xhr = new XMLHttpRequest();
    xhr.open("GET","usm.csv");
    xhr.onreadystatechange = function(){
        if(xhr.readyState == 4){
            if(xhr.status == 200){
                document.getElementById("ajaxResult").innerHTML = xhr.responseText
            }
        }
    };
    xhr.send();
</script>

JSON¶

What is it used for
How to convert from JSON to Javascript object
How does it relate to AJAX

PHP¶

What is PHP used for?
The PHP tag (<?php ?>)
- How to use in HTML, ie if statements
Variables
- $, $$, etc.
- Basic Data Types

In [ ]:

%%script php
<?php
$a = "b";
$b = 10;
echo $$a . " " . $b;

PHP¶

Control Structures
- for/ while
- if, else if, else
- switch
- foreach .. as

In [ ]:

%%script php
<?php
$a = 10;
if($a > 10){
    ?>
    <strong> 10 is less than 10</strong>
    <?php
} else { ?>
     <strong> 10 is not less than 10</strong>   
        <?php }?>

In [ ]:

%%script php
<?php
$list = [10,20,30,40,50];
foreach($list as $el){
    echo $el * 2;
}
?>

PHP¶

Strings
- Interpolation in Strings
- Concatenation with .
- echo

In [1]:

%%script php
<?php 
$a = 10;
echo "This is interpolated: $a";
echo 'This isnt $a';

This is interpolated: 10This isnt $a

Arrays¶

Two Types
- Associative
- Indexed
Declaring
count function
Adding new elements
Sorting

In [ ]:

%%script php
<?php
$indexed = array();
$indexed[] = 1;
$indexed[] = 2;
echo count($indexed);

In [ ]:

%%script php
<?php
$indexed = [1,2];
print_r($indexed);

In [ ]:

%%script php
<?php
$assoc = ['lunes'=>'monday','martes' => 'tuesday','miercoles' => 'wednesday'];
$assoc['jueves'] = 'thursday';
asort($assoc);
print_r($assoc);
ksort($assoc);
print_r($assoc);
sort($assoc);
print_r($assoc);

Functions in PHP¶

Declaring (function) keyword
Scope
- global
Returning from Functions
Pass-by-value is default

In [ ]:

%%script php
<?php
$a = 10;
function scope_tester(){
    $a .= "Hello";
}
scope_tester();
echo $a;

In [ ]:

%%script php
<?php
$a = 10;
function scope_tester(){
    global $a;
    $a .= "Hello";
}
scope_tester();
echo $a;

Files¶

Reading and Writing using file handles
Reading and writing using specialized fucntions
Opening network locations like files
Uploading files with $_FILES

In [ ]:

%%script php
<?php
$fp = fopen("usm.csv",'r');
while($line=fgets($fp)){
    echo $line;
}

In [ ]:

%%script php
<?php
$stuff = file_get_contents("usm.csv");
echo $stuff;

In [ ]:

%%script php
<?php
$stuff = file("usm.csv");
print_r($stuff);

Superglobals¶

What is a subperglobal
How to use $_GET, $_POST, $_SESSION
What type of things are in $_SERVER

PHP Objects¶

How to Define
How to call methods -> syntax

In [ ]:

%%script php
<?php
class Money{
    private $dollars;
    private $cents;
    
    function __construct($d = 0, $c =0){
        $this->dollars = $d;
        $this->cents = $c;
    }
    
    function __toString()
    {
        return '$' . $this->dollars . "." . $this->cents;
    }
    
    function getDollars(){
        return $this->dollars;
    }
}

$currency =  new Money(10,10);
echo $currency;
echo "\n";
echo $currency->getDollars();

Regular Expressions¶

All start with preg_
How matches are stored
How to replace
- What type of data can be used with the replace function

In [ ]:

%%script php
<?php
preg_match("/([\w\.]+)@\w+\.\w\w\w/","My email address is bryan.wilkinson@umbc.edu",$matches);
print_r($matches);

In [ ]:

%%script php
<?php
echo preg_replace('/\*\*(.+?)\*\*/','<strong>$1</strong>',"Outside **Make this Strong**");

Miscellaneous¶

Be able to compare and contrast languages at a high level
- What language might you choose for which task?
Julia
- What it is used for?
- What is unique about it?
Ruby
- What is it used for?
- What are blocks?