C4: Python for Data Science, AI & Development Flashcards
1
Q
str()
A
String data type object.
2
Q
int()
A
Integer data type object.
3
Q
float()
A
Floating Point data type object.
4
Q
list()
A
Returns a list of the elements in an object.
E.g.,
Var = “Panks”
list(Var) : (“P”,”a”,”n”,”k”,”s”)
5
Q
int(3.55):?
A
3
Here you are casting a floating point through a integer data type, which may have strange results.
6
Q
float(15):?
A
15.0
Here you are casting a integer into a floating point data type.
7
Q
str(4.558):?
A
“4.558”
Here you are casting a floating point number into a string data type
8
Q
What are the two Boolean expressions in Python?
A
True & False*.
They must be camel case.
9
Q
int(True):?
A
1
10
Q
int(False):?
A
0
11
Q
bool(1):?
A
True.
12
Q
bool(0):?
A
False.
13
Q
What is an Operand?
A
The thing to be operated on.
14
Q
What is an Operator?
A
What the Operand opperates on.
15
Q
type()?
A
Returns the data type of variable.
Good for debugging.
16
Q
What’s Typecasting?
A
Converting one data type into another.
17
Q
Define Tuple.
A
1) An Ordered set of numbers.
2) Where the order cannot change.
- The sequence cannot be changed.
- Set is finite.
- Set may contain duplicates.
18
Q
n-tuple
A
(X1, … , Xn)
19
Q
What does RegEx mean?
A
Regular Expression.
- A Python module.
- A tool for matching and handling strings.
20
Q
> > > import re
A
Imports the Regular Expression module built into Python 3.
21
Q
Concatenation
A
Combines strings.
22
Q
Major Data Type Objects in Python.
A
Integers
Floating Points
Strings
Booleans
23
Q
Coupoud Data Type Objects? - Python
A
- Lists
- Tuples
24
Q
Tuples syntax? - Python
A
var = (X1,X2,…,…,Xn)
25
For var = **(X1,X2,...,...,Xn)**,
var[0] returns?
X1
26
**Slicing** syntax? - *Python*
[ *n1*:*n2*:*n3*]
Where:
* n1 = The first index position to return.
* n2 = The last index position to pull, +1.
* n3 = The stride, if any.
27
Immutable? - *Python*
Cannot be changed.
E.g.,
* Strings.
* Tuples.
28
List syntax? - *Python*
var = **[X1,X2,...,...,Xn]**
29
Difference between Lists and Tuples?
Lists are mutable. Tupples are not.
30
*var* = [33,55,2,10]
*var***.extend**([9,19])
?
print(*var*) :
[33,55,2,10,9,19]
31
*var* = [33,55,2,10]
*var***.append**([9,19])
?
print(*var*) :
[33,55,2,10,[9,19]]
32
*var* = [33,55,2,10]
**del**(*var*[1]**)**
?
*var* = [33,2,10]
33
What method would you use to convert a string to a list?
**.split()**
E.g.,
str("The rain in spain")
str2 = str.split()
str2 = ["The","rain","in","spain"]
*() is blank, the delimiter is *space*. Otherwise, pass in a delimiter, such as a colon*.
34
Define **Aliasing**.
Multiple names refering to the same object.
35
A = [X1,X2,...,...,Xn]
B = A
list(B) = ?
[X1,X2,...,...,Xn]
36
A = [X1,X2,...,...,Xn]
**B = A[:]**
A[2] = 100
list(A) = ?
list(B) = ?
A = [X1,X2,100,...,...,Xn]
B = [X1,X2,...,...,Xn]
***A[:]*** *clones the list in variable A.*
37
**copy()** - *Python*
A **Method** used to create a shallow copy of a list.
38
**count()** - *Python*
A **Method** used to count the number of occurrences of a *specific element* in a list.
39
Define these **list methods**:
Below, let *"var"*, be any variable that holds a list:
var`.pop()`
var`.reverse()`
var`.sort`
var`.remove()`
var`.insert()`
var`.count()`
var`.copy()`
* `pop()` method is another way to remove an element from a list in Python. It removes and returns the element at the specified index. If you don't provide an index to the `pop()` method, it will remove and return the last element of the list by default
* The `reverse()` method is used to reverse the order of elements in a list
* The `sort()` method is used to sort the elements of a list in ascending order. If you want to sort the list in descending order, you can pass the `reverse=True` argument to the `sort()` method.
* To remove an element from a list. The `remove()` method removes the first occurrence of the specified value.
* The `count()` method is used to count the number of occurrences of a specific element in a list in Python.
* The `copy()` method is used to create a shallow copy of a list.
40
**Dictionaries** object syntax?
`{'`A`':'`a`','`B`':'`b`',...,...,'`N`':'`n`'}`
41
Dictionary attributes.
* Keys must be unique.
* Keys are immutable.
* --
* Values are mutable
* Values don't have to be unique.
42
Assume:
`{'Key1':'Value1','Key2','Value2',...,...,'KeyN','ValueN'}`.
--
If:
**`Dict['Key2']`** :
Value2
43
Assume:
`{'Key1':'Value1','Key2','Value2'}`.
--
If:
**`Dict['New1'] = 100`** :
`{'Key1':'Value1','Key2','Value2','New1':100}`.
44
Assume:
`{'Key1':'Value1','Key2':'Value2','New1':100}`.
--
If:
**`del(Dict['Key1'])`** :
{'Key2':'Value2','New1':100}
45
Assume:
`{'`A`':'`a`','`B`':'`b`',...,...,'`N`':'`n`'}`
--
Query this Dictionary for B.
**`'B' in Dict`** returns `True`
46
`Dict.keys()` : ?
This method lists all the keys in the Dictionary.
47
`Dict.values()` : ?
This method lists all the values in the Dictionary.
48
**`Set`** properties?
* Unordered.
* Containes no duplicate values.
49
**`Set`** object syntax?
`{`3`,`1`,`2`,...,...,`N`}`
50
Typecast a `List` into a `Set`.
`set(`list[x,y,z]`)`
51
Assume:
`var = [3,58,5,5,10,10,8,6]`
--
`set(var)` : ?
**{3,58,5,10,8,6}**
***Note:** A set cannnot contain duplicates. They are removed from the list.*
52
Assume:
`var = {'lake','fire','water'}`
--
`var.add('smores')`
`var` : ?
`{'lake','fire','water','smores'}`
53
Assume:
`var = {'lake','fire','water','smores'}`
--
`var.add('fire')`
`var` : ?
**`var = {'lake','fire','water','smores'}`**
***Note:** A set cannnot contain duplicates. "fire' cannot be added.
54
Assume:
`var = {'lake','fire','water','smores'}`
--
`var.remove('fire')`
`var` : ?
`var = {'lake','water','smores'}`
55
Assume:
`var = {'lake','fire','water','smores'}`
--
**'lake'** `in` **var**: ?
True
56
Set Theory *- Intersection*
Assume:
`Set1 = {1,2,3,4}`
`Set2= {3,4,5,6}`
**Instruct Python to find the *intersection* of both sets.**
Set3 = Set1 `&` Set2
```
*Set3 : {3,4}*
57
Set Theory *- Union*
Assume:
`Set1 = {1,2,3,4}`
`Set2= {3,4,5,6}`
**Instruct Python to find the *union* of both sets.**
Set3 = Set1`.union(`Set2`)`
```
*{1,2,3,4,5,6}*
58
What method clears all the entries from a Dictionary?
var.`clear()`
59
List the six common **Comparison Operators**.
A **==** B - Is A equal to B?
A **!=** B - Is A *not* equal to B?
A **>** B - Is A greater than B?
A **<** B - Is A less than B?
A **>=** B - Is A greater or equal to B?
A **<=** B - Is A less or equal to B?
60
**Comparison Operators** return what?
`True` or `False`.
*These are boolean.*
61
**'Baxter'** `==` **'Baker'**: ?
`False`
```
***Note:*** *String data types _can_ be compared.*
62
`if` syntax?
`if(`condition`) :` *Execute if true.*
______`Indented code.`
______`Indented code.`
```
***Note:*** *Indents are _required_.*
63
`if / else` syntax?
`if(`condition`) :` *Execute if true.*
______`Indented code.`
______`Indented code.`
`else:` *Execute if above is false.*
______`Indented code.`
______`Indented code.`
```
***Note:*** *Indents are _required_.*
64
`if / elif / else` syntax?
`if(`condition`) :` *Execute if true.*
______`Indented code.`
______`Indented code.`
`elif(`condition`) :` *Execute if above is false & this is true.*
______`Indented code.`
______`Indented code.`
`else:` *Execute if both above are false.*
______`Indented code.`
______`Indented code.`
```
***Note:*** *Indents are _required_.*
65
Logic Operators ?
`not()`
`or()`
`and()`
*Python supports these three logic operators.*
66
if(True) `and` (False): ?
False
67
if(True) `or` (False): ?
True
68
**range(N)**
or
**range(0,N)**
[0,1,2,...,...,N-1]
***Note:***
* *The last value of arange function is always **one less** than the number input into the function.*
* *A range sequence always starts at **0***.
* *N must be a an **whole number***.
69
**range(10,15)** : ?
[10,11,12,13,14]
70
`i` in **`for`** loops?
`Index` or `increment`.
71
Incement `i` by 1.
Decrement `i` by 5.
i `+=` 1
i `-=` 5
72
`for` syntax?
`for` counter `in` iterable object `:`
______`Indented code.`
______`Indented code.`
```
***Note:***
* *`for` will increment the **"counter"** at the end of each loop.*
* **"counter"** *can be any variable that can hold an integer data type. It is usualy `i`.
* It is a temporary variable that is constrained in scope to the loop.*
73
`while` syntax?
`while` some conditional True `:`
______`Indented code.`
______`Indented code.`
***Note:***
* *It is not uncommon to itterate some counter variable within the `while` loop.*
74
`list(enumerate(range(11)))` : ?
[(0, 0),
(1, 1),
(2, 2),
(3, 3),
(4, 4),
(5, 5),
(6, 6),
(7, 7),
(8, 8),
(9, 9)
(10,10)]]
75
`Function` syntax ?
`def` **function_name**`(`*Argument(s)*`):`
______"""
______Notes
______"""
______`Indented code.`
______`return` **b**
```
***Note:***
* *Functions cannot have an empty body. Use `none` in the body satsify this requirement that the function not be blank.*
* *You do not have to define a `return` in a function.*
76
Do Local Variables confilict with Global Variables?
**No.**
Variables inside a functon do not change variables outside a function, even if they have the same name.
77
What will Python do if if finds an undefined variable in a function?
Check for the variable in the global scope.
78
What does `pass` do in a function?
* **Acts as a temporary placeholder for future code.**
* It ensures that the code remains syntactically correct, even if it doesn't do anything yet.
* Doesn't perform any meaningful action. When the interpreter encounters “pass”, it simply moves on to the next statement without executing any code.
79
Define **Global Scope** variables.
Variables defined outside functions; accessible everywhere.
80
Define **Local Scope** variables.
Variables inside functions; only usable within that function.
81
What does `global` do in a function?
**Changes the scope of a variable in the function from local to global.**
Meaning that it can be referenced even after the function has completed.
82
How would you modify the following function to allow you to pass in a variable number of arguments?
```
`def` **a_function**`(`*argument*`):`
______"""
______Notes
______"""
______`Indented code.`
______`return` **b**
**Place an asterisk before the argument.**
```
E.g., *`def` **a_function**`(`* *argument`):`
83
`Try` syntax?
`try:`
______code or pass
`except` *Exception*`:`
______code or pass
`except` *Exception*`:`
______code or pass
`else:`
______code or pass
`finally:`
______code or pass
84
Complete the sentence:
**Methods are "..." with Objects.**
*...how you change or interact...*
85
Class > Object > **?** > Method
Attribute.
86
**?** > Object > Attribute > Method
Class
87
Class > **?** > Attribute > Method
Object
88
Class > Object > Attribute > **?**
Method
89
A **class** is a template for?
Objects.
90
**Class** syntax?
`class` *className*`():`
______`class_attribute = value`
______`def` `_``_``init``_``_``(self,` attribute1, attribute2, ...`):`
____________`self.attribute1 = attribute1`
____________`self.attribute2 = attribute2`
____________`...`
______def method1(self, `parameter1, parameter2, ...`):`
____________`Method logic`
____________`...`
```
* Class attributes (shared by all instances).
* Constructor method (initialize instance attributes).
* Instance methods (functions). Do not have to have a value passed.
91
An objects attributes define it's?
**State**.
A.k.a., The data that describes the object.
92
An objects methods define it's?
**Behavior.**
A.k.a., Actions assigned to the object that can change it's *state.*
93
An Object is an ... of a Class?
Instance.
94
Name the two loop controls.
Break.
Continue.
95
What does `dir(`*object*`)` do?
**Returns all properties and methods of the specified object**, without the values.
96
Open a file syntax?
`open(`*.../path/filename.txt`,`'**x**'`)`
```
*Where:*
* *The value of **x** may be:
* **r** for reading mode.
* **w** for writing mode.
* **a** for appending mode.
97
fileObject**.name()** returns?
**The name of the file** in the file object.
98
*Open the following file in append mode inside a file object named* `darth` *:*
```
**.../path/tothe.darkside**
`with` `open('`*.../path/tothe.darkside*`','a') as darth`
99
fileObject**.read()** ?
**Reads the entire content of the file.**
e.g., darth = *vader*`.read()`
100
fileObject**.read(**`x`**)** ?
**Reads **`x`** characters starting from the current position of the file pointer.**
e.g., darth = *vader***.read(**`10`**)**
101
fileObject**.readline()** ?
**Reads the contents of a file line by line.**
*Note, it remembers where it last read. Then _itterates_ and reads the next line if called again. Also, if given an integer as an argument, it will read tham many posisitons of that line. But _only_ from that line.*
102
fileObject**.seek(x)** ?
**Moves the files pointer to a specific position in the file. Then reads that character.**
*The position is specified in bytes, so you'll need to know the byte offset of the characters you want to read.*
103
fileObject**.close()** ?
**Closes a file.**
_This is essential._
*However, you should not have to use this if you are using the *`with`* method.*
104
Create a new file in the local directory named `obiwan.master` mapped to a file object named `jedi`.
`with open('`*.../path/tothelight/*`obiwan.master','w') as jedi:`
```
*Note:*
**If the file requested by open _does not exist_ in the directory, the action will create it.**
105
**Dependencies** is another name for ?
Libraries.
106
**.tell()** does what?
Returns where the system caret `^` is in the file object.
107
Diferentiate the following;
`.readline()
.readlines()`
`.readline()`:
This method returns one full line from the file object as a string.
`.readlines()`:
This method returns all the line in a file object as a list.
108
How do you querying a variable for it's attributes and methods?
`dir(`*var*`)`
109
Load pandas?
`import` *pandas* `as` pd
110
*With pandas imported:*
`df.head()` does what?
Prints the first five rows of the data frame.
111
* *With pandas imported:*
* *Assume `var` is a dictionary.*
```
How would you cast the dictionary into a dataframe?
varInFrame = `pd.DataFrame(`*var*`)`
112
*With pandas imported:*
When you cast a *dictionary* into a *data frame*, the **values** become?
Columns.
```
*The keys become the column headers.*
113
*With pandas imported:*
How would you pull an entire column(s) from a data frame and make it a new object?
var =` df [[ ` *'key1' , 'key2' , 'key5'* `]]`
*Double brackets extracts a column by key (header)name.*
114
* *With pandas imported +*
* *An active data frame, `df`:*
How would you reference cell **a1**?
df.`iloc[0,0]`
115
*With pandas imported:*
Read a *decks.csv* into the data frame object, `df`.
`df` = `pd.read_csv('`*decks.csv*`')`
116
* *With pandas imported:*
* *Assume:* `data = [10, 20, 30, 40, 50]`
**Create a series in series object** `s` **from this list.**
s = pd.Series(data)
117
Diferentiate,
print(df.`iloc`[n])
*from*
print(df.`loc`[n])
`iloc` **accesses the row by _position_.**
*iloc[row_index, column_index]*
*i.e., index location.*
**Counts from 0.**
```
`loc` **acesses the row by _label_**
*loc[row_label, column_label]*
*Use method set_index() to set a columns contents as the index from the default.*
**Counts from 1.**
118
Pandas generally provides **two data structures for manipulating data,** They are?
Data Frames.
Series.
119
df`.iloc[1:3]`
vs.
df`.iloc[1,3]`
The first **slices** out and returns rows 2 & 3.
The second **selects** the data a row 2 / column 3.
120
What is `df.iloc[0:2, 0:3]` doing?
Slicing out the first two rows, three columns deep.
121
NumPy stands for?
Numerical Python.
122
NumPy is meant for working with?
* Arrays
* Linear algebra
* Fourier transforms
* Matrices
123
The 'Pandas library' is built on?
The NumPy library.
124
Syntax for making a **2D array** in Python with`NumPy`?
my_2d_array = `np.array [`
_________________________`[0,0,0,0,0,0],`
_________________________`[0,0,0,0,0,0],`
_________________________`[0,0,0,0,0,0],`
_________________________`[0,0,0,0,0,0],`
_________________________`[0,0,0,0,0,0],`
_________________________`],`
125
if `var` is an numpy array what do these methods do?
var**.dtype**
var**.size**
var**.ndim**
var**.shape**
var**.dot()**
var**.mean()**
var**.max()**
var**.min()**
var**.std()**
`.dtype` returns the type of the data stored in the array.
`.size` returns the number of elements in the array.
`.ndim` returns the number of dimensions of the array.
`.shape` returns the length of each dimension of the array.
`.dot(a,b)` returns the dot product of the np arrays a and b.
`.mean()` returns the mean value of the array.
`.max()` returns the max value of the array.
`.std()` returns the standard deviation of the array.
126
**np.pi** ?
Return the value of pi.
127
**np.linspace(a,b,c)**
**np.linspace(a,b,c)** returns a line (a list) starting at 'a' and ending at 'b' with 'c' evenly spaced intevals as a array. (Which include the intervals 'a' and 'b'.
128
What does **URI** stand for?
**Uniform resource identifier.**
This is distinct from a *URL*.
129
What are the four HTTP methods?
**GET**: Retrieves data from the Server or API.
**POST**: Submits data to the Server or API.
**PUT**: Updates data on the Server or API.
**DELETE**: Deletes data on the the Server or in the API.
130
What does the `Requests` library do?
Allows you to make HTTP 1.1 requests from within Python.
131
A URL has three parts.
They are?
**Scheme.
Address.
Path.**
e.g.,
https://
www.google.com
/a/admin/login
132
Which contanins which?
URL
URI
**Uniform Resource Identifier > Uniform Resource Locator**
or
*URI {URL}*
133
What are the 5 HTTP **response status code classes** and their general meaning?
100: *Info.*
200: *Success.*
300: *Make a choice.*
400: *Failure*.
500: *Big failure.*
134
HTML tags hierarchy?
Parent > Child > Decendent
Siblings = Siblings
135
What is `Beautiful Soup`?
A module that facilitates webscraping.
136
What does **DOM** stand for?
Document Object Model
137
