# Unit 4 Lists, Tuples and Dictionaries *To contribute/fix, fork and edit the corresponding file* [*here*](https://kgisl.gitbook.io/lab3003/notes/cs3003-unit4) * Lists: list operations, list slices, list methods, list loop, mutability, aliasing, cloning lists, list parameters; Tuples: tuple assignment, tuple as return value; Dictionaries: operations and methods; * Advanced list processing - list comprehension * For last section of Unit 4, `Illustrative Programs`, please see Pre-requisite: (Needs updation) *Refer to the* [*glossary*](#glossary) *below to become familiar with the terms relevant to this unit* I just scored 63% on @realpython's "Python Lists and Tuples" quiz. What's your score? #pythonquiz ## Concept Map *A picture is worth a 1000 words* ![mutableList](https://files.gitter.im/kgashok/advik/TYg6/mutableLists.png) ## Sequences and attributes Here are some important methods that are associated with `tuple`, `list` and `dictionary` - all types that are covered in Unit 4. | Type | Attributes | | --------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------- | | `'tuple'` | 8 **`count`**, `index` | | `'list'` | 9 **`append`**, `clear`, `copy`, 10 **`count`**, 11 **`extend`**, `index`, 12 **`insert`**, 13 **`pop`**, 14 **`remove`**, 15 **`reverse`**, 16 **`sort`** | | `'dict'` | `clear`, `copy`, `fromkeys`, 17 **`get`**, 18 **`items`**, 19 **`keys`**, 20 **`pop`**, `popitem`, `setdefault`, 21 **`update`**, 22 **`values`** | ## List Methods and Operations The following table has been created by ***clustering*** multiple items based on some criteria. This is easier to internalize and deliver to maximize retention among students. Moreover, there is going to be *better* chance of overall engagement. * What is a list **method** (an attribute of a variable)? What is a list **operation** (a stand-alone function)? What is the difference? Get this clarified *first*! | Intent | Method / Operation | Description | | ---------------------- | --------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------- | | **Initialize** methods | *none* | initialize an empty list, using a tuple, using another list | | *operations* | `[]`, `list()` or `list(sequence)`, the `=` operator | `bl = al` initializes `bl` as an **alias** for the`al` list object | | **Access** methods | \[*idx*], `.index(elem)`\[1] `.count()`\[2] | `index` throws an exception if not present | | *operations* | `in` and `not in`, `any` and `all`, `max`, `min`, `len`, `sum` | membership `in` list, `all` or `any` if element(s) is `True` | | **Modify** methods | *addition* `.append(val)`\[3], `.insert(loc, val)`\[4], `.extend(lst)`\[5] | add elements to the list at specific locations; `extend` adds multiple elements from sequence | | | *extraction* `.pop(loc)`\[6], `.remove(elem)`\[7], `.clear()`\[8] | take out from specified index, or element or all elements | | | *ordering* `.reverse()`\[9], `.sort()`\[10] | rearrange elements in the list | | *operations* | `del`, `sorted` | same effect as the methods with better performance? | | **Allocate** methods | `.copy()`\[11],`[:]`, \[*s*:*s*:*s*], repetition (using `*`) and concatenation (using `+`) | Create distinct list objects by duplicating existing ones | | *operations* | slice(*start*, *stop*, *step*), `zip`, `enumerate`, **cloning** (*copy.copy and deepcopy*) and **list comprehension** | same as slice operator `[]`, `zip` creates a new list with tuples from two lists, `enumerate` provides list with (*index*, *element*) tuple | ![disp](https://2586751836-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-L9clfk8zn6i_b1EBzGy%2Fuploads%2Fgit-blob-2af4e81d34a52decf2489eee911bbf3bc6bbd15d%2FlistMethodsInAction.jpeg?alt=media) ## List indexing * - swap elements in a list ## List Mutability - explanation of Immutability in Python Pre-requisite: From [https://jeffknupp.com/blog/2012/11/13/is-python-callbyvalue-or-callbyreference-neither/](https://web.archive.org/web/20201203041546/https://www.jeffknupp.com/blog/2012/11/13/is-python-callbyvalue-or-callbyreference-neither/) This brings us to an important point: there are actually two kinds of objects in Python. A *mutable* object exhibits time-varying behavior. Changes to a mutable object are visible through all names bound to it. Python's lists are an example of mutable objects. An *immutable* object does not exhibit time-varying behavior. The value of immutable objects can not be modified after they are created. They *can* be used to compute the values of **new** objects, which is how a function like string.join works. When you think about it, this dichotomy is necessary because, again, everything is an object in Python. If integers were not immutable I could change the meaning of the **number '2'** throughout my program. It would be incorrect to say that *"mutable objects can change and immutable ones can't"*, however. ![passs](https://2586751836-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-L9clfk8zn6i_b1EBzGy%2Fuploads%2Fgit-blob-4906c5d640944b862ac8341ee904aa64b69d1210%2FpythonCallByValue.png?alt=media) ## Slicing * **A Python slice** extracts elements from an `iterable` based on a start and stop. It returns a `iterable` (or sequence) containing the extracted elements. * We take slices on many types (`string, list and/or tuple`) in Python. * We specify an optional `start` index, an optional `stop` index, and an optional `step` value (`0` is not acceptable as step value). **Syntax notes.** The special syntax for this operation is at first confusing. But with practice, slicing becomes easy. When we omit a value, a default is used. ### \[Start: Stop: Step] | Slice | Description | | --------------- | ----------------------------------------------------- | | `values[1:3]` | Index 1 through index 3. | | `values[2:-1]` | Index 2 through index one from last. | | `values[:2]` | Start through index 2. | | `values[2:]` | Index 2 through end. | | `values[::2]` | Start through end, skipping ahead 2 places each time. | | **`values[:]`** | Returns a copy of the list with all elements | ```python rlist = [88, 44, 65, 68, 78, \ 23, 72, 28, 50, 72, 21, 47, 27, 50, 15] What does rlist[:-10] evaluate to? # [88, 44, 65, 68, 78] What does rlist[:-10:3] evaluate to? # [88, 68] alist = [25, 20, 25, 84, 67, 99, 96, 67,\ 27, 78, 73] [-3:7:-1] What does `alist` contain? ``` * Slice operator * Slicing of Lists * * Slice Detailed Slides ## List Comprehension Pre-requisite; and List comprehensions are concise ways to create lists. The general syntax is: ``` [ for in if ] ``` where the `if` clause is optional. For example, ```python mylist = [1,2,3,4,5] yourlist = [item ** 2 for item in mylist] print(yourlist) # [1, 4, 9, 16, 25] ``` ### Quiz 1. What is printed by the following statements? Or, what is the output of the following statements? ```python alist = [4,2,8,6,5] blist = [num*2 for num in alist if num%2==1] print(blist) ``` ``` (A) [4,2,8,6,5] (B) [8,4,16,12,10] (C) 10 (D) [10] ``` 2. - manually code out the enumerate function 3. Find the output for these list comprehensions ![compre](http://j.mp/compreThis) 1. Complete the code snippet to loop through the list in reverse and then print it out. ```python pylist = ['n', 'o', 'h', 't', 'y', 'p'] for c in ???(???): ???(c) ``` ## Eight Ways to copy/clone a list? *Using functions/operations* 1. Use slicing - `bl = al[:]` (apparently, the fastest technique) 2. Use list comprehension `bl = [elem for elem in al ]` 3. Use `list()` function *Using methods* 4. Use the `.copy` method - `bl = al.copy()` 5. Using `.extend` method 6. Using `.append` method *Using modules* 7. Use the `copy.copy` function 8. Use the `copy.deepcopy` function ## Four ways to reverse a list 1. Use `reverse`method - `al.reverse()` 2. Use slice `al = al[::-1]` * Can you use`slice` to reverse the list, in place? 3. Use `reversed` function - `list (reversed(al))` 4. Write your own `reverseList` function using a loop ## Four ways to swap 2 values 1. Use a temp variable > temp = a a = b b = temp 2. Use addition and subtraction > a = a + b b = a - b\ > a = a - b 3. Using XOR > a ^= b b ^= a a ^= b 4. Using tuple assignments > tuple assignment > An assignment to all of the elements in a tuple using a single assignment statement. Tuple assignment occurs *simultaneously* rather than in sequence, making it useful for swapping values. a, b, = (b, a) 5. Using list methods > al = \[a, b] a = al.pop() b = al.pop() ## List Parameters - what is the difference between parameters and arguments? [Python has no pass by value](https://medium.com/@george.smith2024/there-is-no-pass-by-value-in-python-5a0efa544736?source=responses---------13-----------------------) There is no pass by value in Python. Functions arguments are always passed by reference (or object reference, to be exact). The reason that numbers don’t change even if they are passed by reference is because of their immutability. [Refer book section for more details](https://runestone.academy/runestone/static/thinkcspy/Lists/UsingListsasParameters.html) ## Sequence Assignment, Packing, Unpacking This is very unique to the Python language in that you can do multiple assignments in the same statement. For coming up with the function for determining whether a string is a palindrome, it works quite elegantly. ![tuple](https://2586751836-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-L9clfk8zn6i_b1EBzGy%2Fuploads%2Fgit-blob-e4eb85226960990b1477b1f36e424615f31b57b2%2FpalindromeUnpack.png?alt=media) ## Dictionary A collection of key-value pairs that maps from keys to values. The keys can be any immutable type, and the values can be any type. Dictionaries implement the [associative array](http://en.wikipedia.org/wiki/Associative_array) abstract data type. **key**: A data item that is *mapped to* a value in a dictionary. Keys are used to look up values in a dictionary. **key-value pair**: One of the pairs of items in a dictionary. Values are looked up in a dictionary by key. ``` adict = dict() # initialization adict['Sam'] = 233-2333 adict['Victor'] = 900-2222 ``` ### Exercises * Tackle a Cloudcoder exercise - generate a dictionary or a list of tuples. * * ## Glossary **aliases** Multiple variables that contain references to the same object. * aliasing - nicknames - multiple names for the same object * Rajesh is the name of a boy; 'Ramki' might be the name used by his close relatives; "Bondaaaa" might be the name used by his close friends; 'Ramki' and "Bondaaa" are **aliases** (nicknames) for Rajesh **clone** To create a new object that has the same value as an existing object. Copying a reference to an object creates an alias but doesn’t clone the object. * Cloning a goat using stem cells is about duplicating what is already available **delimiter** A character or string used to indicate where a string should be split. **element** One of the values in a list (or other sequence). The bracket operator selects elements of a list. **index** An integer variable or value that indicates an element of a list. **list** A collection of objects, where each object is identified by an index. Like other types `str`, `int`, `float`, etc. there is also a `list` type-converter function that tries to turn its argument into a list. **list traversal** The sequential accessing of each element in a list. **modifier** A function which changes its arguments inside the function body. Only mutable types can be changed by modifiers. **mutable data type** A data type in which the elements can be modified. All mutable types are compound types. Lists are mutable data types; strings are not. * mutability - > ability to mutated, to be changed, to be modified * immutability -> cannot be changed **nested list** A list that is an element of another list. **object** A thing to which a variable can refer. **sequence** Any of the data types that consist of an ordered collection of elements, with each element identified by an index. **tuple** A sequential collection of items, similar to a list. Any python object can be an element of a tuple. However, unlike a list, tuples are immutable. ## Exercises 1 [Runestone exercises](https://runestone.academy/runestone/static/thinkcspy/Lists/Exercises.html)\ 2\. **Remove duplicates.** A list contains duplicate elements. How can we remove them? Some approaches may lead to the elements becoming reordered, but this is not necessary. ## Exercises for Illustrative Programs * and - iterate over a list * - traverse and do a summation * - right shift exactly by one position * * - swap elements in a list * - manually code out the enumerate function * - divide a list into two halves ## Slice Exercises - Part 0 * - right shift exactly by one position * and * - divide a list into two halves * - from repl course for Python * Given a list, cut it into two equal parts. If the length of the list is odd, leave the middle item within the first chunk, so that the first list contains one more character than the second. Now print a new list on a single row with the first and second halves swapped: second half first and the first half last. ## Slice Exercises - Part 1 ```python 0. [35, 67, 41, 25, 31, 100, 97, 80][1:7] slice(1,7,2) or [1:7:2] 2. [37, 17, 24, 82, 10, 52, 62, 36, 77, 88, 30, 13][-9:] slice(-9,None,-3) or [-9::-3] 3. [37, 52, 52, 54, 97, 88, 76, 28, 45][10:11] slice(10,11,0) or [10:11:0] 4. [40, 21, 54][2:] slice(2,None,1) or [2::1] 5. [69, 34, 94, 55, 41, 10, 83, 43][-2:] slice(-2,None,-2) or [-2::-2] 6. [50, 86, 76, 10, 37, 74, 71, 99, 87, 73, 13, 17, 45] slice(-12,None,6) or [-12::6] 7. [42, 13, 79, 33, 45, 72, 51, 26, 34][7:] slice(7,None,-2) or [7::-2] 8. [70, 26, 33, 35, 67][-7:] slice(-7,None,1) or [-7::1] 9. [98, 88, 96, 32, 27, 66, 65, 79, 99] slice(-9,None,-1) or [-9::-1] 15. [58, 77] slice(-1,-5,-1) or [-1:-5:-1] 20. [31, 83, 70, 44, 16, 29, 100, 88, 10, 96, 37, 53, 58][-2:] slice(-2,None,3) or [-2::3] 23. [10, 71][1:] slice(1,None,-1) or [1::-1] 25. [80, 39, 71, 29, 38, 98, 47, 63, 89, 38, 90, 91, 20][-16:] 29. [76, 26, 14, 45][3:] slice(3,None,-3) or [3::-3] 32. [25, 71, 15, 78, 53] slice(-1,-5,-1) or [-1:-5:-1] 34. [94, 21, 69, 25, 20, 69, 75, 13, 55, 83, 44][-14:] 42. [83, 43, 21, 70, 18, 52, 53, 89][7:] 43. [56, 34, 23, 18, 96, 29, 49, 82, 12][6:] slice(6,None,-3) or [6::-3] 46. [71, 80, 86, 31, 91, 86][4:] slice(4,None,-1) or [4::-1] 48. [38, 19, 98, 20, 29, 63, 24, 60, 53, 80][-3:] slice(-3,None,-2) or [-3::-2] 49. [49, 77, 55, 58, 75, 66, 97, 12, 77, 80, 44, 54][-5:] slice(-5,None,2) or [-5::2] 50. [94, 86, 51, 95, 87, 70][-1:] 51. [56, 82, 13, 61, 79, 99, 62, 48, 66, 61, 40][-9:] slice(-9,None,-2) or [-9::-2] 54. [16, 86, 42, 47, 75, 88, 17, 66, 60, 95, 97, 48][7:11] slice(7,11,-1) or [7:11:-1] 56. [81, 95, 99, 26, 85, 91, 25, 97, 69, 53, 92, 51] slice(-3,-14,-3) or [-3:-14:-3] 60. [91, 96, 35, 18, 63, 83][1:] 63. [37, 99, 31][-2:] 65. [22, 48, 80, 72, 28, 16, 60, 21, 54, 24, 57][-9:] slice(-9,None,2) or [-9::2] 67. [84, 80, 38, 51, 44, 57, 25, 56, 82, 14, 37][1:4] slice(1,4,0) or [1:4:0] 68. [70, 90, 71, 67, 78, 99, 18, 44][5:] slice(5,None,-2) or [5::-2] ``` ## Slice Keys - Part 1 ```python 0.[35, 67, 41, 25, 31, 100, 97, 80][1:7] [67, 41, 25, 31, 100, 97] 0. slice(1,7,2) or [1:7:2] [67, 25, 100] 2.[37, 17, 24, 82, 10, 52, 62, 36, 77, 88, 30, 13][-9:] [82, 10, 52, 62, 36, 77, 88, 30, 13] 2. slice(-9,None,-3) or [-9::-3] [82, 37] 3.[37, 52, 52, 54, 97, 88, 76, 28, 45][10:11] [] 3. slice(10,11,0) or [10:11:0] [82, 37] 4.[40, 21, 54][2:] [54] 4. slice(2,None,1) or [2::1] [54] 5.[69, 34, 94, 55, 41, 10, 83, 43][-2:] [83, 43] 5. slice(-2,None,-2) or [-2::-2] [83, 41, 94, 69] 6. [50, 86, 76, 10, 37, 74, 71, 99, 87, 73, 13, 17, 45] slice(-12,None,6) or [-12::6] [86, 99] 7.[42, 13, 79, 33, 45, 72, 51, 26, 34][7:] [26, 34] 7. slice(7,None,-2) or [7::-2] [26, 72, 33, 13] 8.[70, 26, 33, 35, 67][-7:] [70, 26, 33, 35, 67] 8. slice(-7,None,1) or [-7::1] [70, 26, 33, 35, 67] 9. [98, 88, 96, 32, 27, 66, 65, 79, 99] slice(-9,None,-1) or [-9::-1] [98] 15. [58, 77] slice(-1,-5,-1) or [-1:-5:-1] [77, 58] 20.[31, 83, 70, 44, 16, 29, 100, 88, 10, 96, 37, 53, 58][-2:] [53, 58] 20. slice(-2,None,3) or [-2::3] [53] 23.[10, 71][1:] [71] 23. slice(1,None,-1) or [1::-1] [71, 10] 25. [80, 39, 71, 29, 38, 98, 47, 63, 89, 38, 90, 91, 20][-16:] [80, 39, 71, 29, 38, 98, 47, 63, 89, 38, 90, 91, 20] 29.[76, 26, 14, 45][3:] [45] 29. slice(3,None,-3) or [3::-3] [45, 76] 32. [25, 71, 15, 78, 53] slice(-1,-5,-1) or [-1:-5:-1] [53, 78, 15, 71] 34. [94, 21, 69, 25, 20, 69, 75, 13, 55, 83, 44][-14:] [94, 21, 69, 25, 20, 69, 75, 13, 55, 83, 44] 42. [83, 43, 21, 70, 18, 52, 53, 89][7:] [89] 43.[56, 34, 23, 18, 96, 29, 49, 82, 12][6:] [49, 82, 12] 43. slice(6,None,-3) or [6::-3] [49, 18, 56] 46.[71, 80, 86, 31, 91, 86][4:] [91, 86] 46. slice(4,None,-1) or [4::-1] [91, 31, 86, 80, 71] 48.[38, 19, 98, 20, 29, 63, 24, 60, 53, 80][-3:] [60, 53, 80] 48. slice(-3,None,-2) or [-3::-2] [60, 63, 20, 19] 49.[49, 77, 55, 58, 75, 66, 97, 12, 77, 80, 44, 54][-5:] [12, 77, 80, 44, 54] 49. slice(-5,None,2) or [-5::2] [12, 80, 54] 50. [94, 86, 51, 95, 87, 70][-1:] [70] 51.[56, 82, 13, 61, 79, 99, 62, 48, 66, 61, 40][-9:] [13, 61, 79, 99, 62, 48, 66, 61, 40] 51. slice(-9,None,-2) or [-9::-2] [13, 56] 54.[16, 86, 42, 47, 75, 88, 17, 66, 60, 95, 97, 48][7:11] [66, 60, 95, 97] 54. slice(7,11,-1) or [7:11:-1] [] 56. [81, 95, 99, 26, 85, 91, 25, 97, 69, 53, 92, 51] slice(-3,-14,-3) or [-3:-14:-3] [53, 25, 26, 81] 60. [91, 96, 35, 18, 63, 83][1:] [96, 35, 18, 63, 83] 63. [37, 99, 31][-2:] [99, 31] 65.[22, 48, 80, 72, 28, 16, 60, 21, 54, 24, 57][-9:] [80, 72, 28, 16, 60, 21, 54, 24, 57] 65. slice(-9,None,2) or [-9::2] [80, 28, 60, 54, 57] 67.[84, 80, 38, 51, 44, 57, 25, 56, 82, 14, 37][1:4] [80, 38, 51] 67. slice(1,4,0) or [1:4:0] [53, 52] 68.[70, 90, 71, 67, 78, 99, 18, 44][5:] [99, 18, 44] 68. slice(5,None,-2) or [5::-2] [99, 67, 90] ``` ## Slice Exercises - Part 2 ```python 0. [93, 32, 55, 34, 11][4:] 1. [84, 32, 21, 89, 27, 82, 72, 47, 96, 93][11:] slice(11,None,-2) or [11::-2] 2. [73, 67, 35, 40, 40, 25, 91, 56, 91, 75, 16][-3:] slice(-3,None,-1) or [-3::-1] 3. [50, 65, 90, 98, 38, 24, 52, 60, 32, 11, 11, 99, 28][2:] slice(2,None,0) or [2::0] 4. [76, 42, 65, 14, 69, 41, 23, 38][-11:] 5. [60, 98, 42, 15, 33, 96, 15, 35, 80, 78][3:] slice(3,None,-1) or [3::-1] 9. [65, 75, 77][2:] 10. [13, 87, 47, 15, 59, 19, 80, 88, 55, 47, 66, 10][11:12] 12. [100, 21, 85, 56, 53, 42, 87, 38, 50, 51, 63, 23] slice(2,None,2) or [2::2] 13. [89, 61, 35, 32][-1:] slice(-1,None,-1) or [-1::-1] 14. [66, 70, 26, 84, 51, 11, 95, 86, 59, 27, 59, 61][-12:] slice(-12,None,-2) or [-12::-2] 15. [63, 18, 48, 10, 49, 67, 52, 57][0:0] 16. [61, 16, 14, 63, 22, 36, 42, 17][6:] 19. [58, 11, 55, 12, 41][3:6] 20. [17, 46, 17, 81, 46, 71, 53, 16, 23, 72] slice(2,None,-1) or [2::-1] 24. [38, 95, 83, 34, 40, 18, 42, 29][-4:] 28. [74, 15, 17, 77, 16, 91][1:] slice(1,None,2) or [1::2] 29. [76, 23, 55, 70, 59, 83, 26, 91][-5:] 30. [80, 62][1:2] 31. [83, 81, 100, 51, 69, 38, 24, 74, 29, 61, 87, 79, 72][10:14] slice(10,14,1) or [10:14:1] 39. [34, 54, 18, 42, 53][-2:] slice(-2,None,-2) or [-2::-2] 41. [99, 49, 14][-2:] 42. [18, 35, 33, 19, 63, 69, 77, 68, 47, 63, 69, 99][-3:] 45. [90, 52, 10, 15, 42, 43, 32, 39] slice(2,None,4) or [2::4] 48. [45, 23, 57, 60, 11, 10, 66, 57, 27, 30, 19] slice(8,None,1) or [8::1] 55. [37, 15, 31, 66, 77][4:] 57. [94, 11, 72, 87] slice(3,None,-1) or [3::-1] 58. [50, 78, 100, 14, 34, 30, 25, 24, 53, 73, 57][8:] slice(8,None,-2) or [8::-2] 59. [95, 73, 62, 71, 88, 41, 83][:0] 60. [100] slice(1,None,-1) or [1::-1] 61. [13, 41, 31, 71, 23, 45, 84, 41, 15][4:] slice(4,None,3) or [4::3] 62. [32, 84, 71][-2:] slice(-2,None,1) or [-2::1] 64. [68, 11, 26][1:] slice(1,None,-1) or [1::-1] 67. [52, 52, 91, 10, 74, 12, 20, 23, 16, 47][-7:] slice(-7,None,1) or [-7::1] 68. [100, 100, 60, 86, 86, 28, 97, 52, 56, 72, 44][-3:] 69. [30, 79, 20, 28, 48, 71, 81, 57, 19, 16, 34, 94][0:-13] 70. [41, 53, 13, 59, 39, 31][2:] slice(2,None,1) or [2::1] 71. [90, 86, 50, 96, 90, 81][3:] 72. [66, 23, 63, 92, 51, 24, 16, 34, 59, 56, 21, 19][-5:] slice(-5,None,1) or [-5::1] 74. [58, 59, 57, 92, 96, 91, 74, 24, 36, 83, 43, 88][0:-3] slice(None,-3,-1) or [0:-3:-1] 77. [85, 26, 74, 85, 39, 77, 98][1:] slice(1,None,2) or [1::2] ``` ## Slice Keys - Part 2 ```python 0. [93, 32, 55, 34, 11][4:] [11] 1.[84, 32, 21, 89, 27, 82, 72, 47, 96, 93][11:] [] 1. slice(11,None,-2) or [11::-2] [93, 47, 82, 89, 32] 2.[73, 67, 35, 40, 40, 25, 91, 56, 91, 75, 16][-3:] [91, 75, 16] 2. slice(-3,None,-1) or [-3::-1] [91, 56, 91, 25, 40, 40, 35, 67, 73] 3.[50, 65, 90, 98, 38, 24, 52, 60, 32, 11, 11, 99, 28][2:] [90, 98, 38, 24, 52, 60, 32, 11, 11, 99, 28] 3. slice(2,None,0) or [2::0] [91, 56, 91, 25, 40, 40, 35, 67, 73] 4. [76, 42, 65, 14, 69, 41, 23, 38][-11:] [76, 42, 65, 14, 69, 41, 23, 38] 5.[60, 98, 42, 15, 33, 96, 15, 35, 80, 78][3:] [15, 33, 96, 15, 35, 80, 78] 5. slice(3,None,-1) or [3::-1] [15, 42, 98, 60] 9. [65, 75, 77][2:] [77] 10. [13, 87, 47, 15, 59, 19, 80, 88, 55, 47, 66, 10][11:12] [10] 12. [100, 21, 85, 56, 53, 42, 87, 38, 50, 51, 63, 23] slice(2,None,2) or [2::2] [85, 53, 87, 50, 63] 13.[89, 61, 35, 32][-1:] [32] 13. slice(-1,None,-1) or [-1::-1] [32, 35, 61, 89] 14.[66, 70, 26, 84, 51, 11, 95, 86, 59, 27, 59, 61][-12:] [66, 70, 26, 84, 51, 11, 95, 86, 59, 27, 59, 61] 14. slice(-12,None,-2) or [-12::-2] [66] 15. [63, 18, 48, 10, 49, 67, 52, 57][0:0] [] 16. [61, 16, 14, 63, 22, 36, 42, 17][6:] [42, 17] 19. [58, 11, 55, 12, 41][3:6] [12, 41] 20. [17, 46, 17, 81, 46, 71, 53, 16, 23, 72] slice(2,None,-1) or [2::-1] [17, 46, 17] 24. [38, 95, 83, 34, 40, 18, 42, 29][-4:] [40, 18, 42, 29] 28.[74, 15, 17, 77, 16, 91][1:] [15, 17, 77, 16, 91] 28. slice(1,None,2) or [1::2] [15, 77, 91] 29. [76, 23, 55, 70, 59, 83, 26, 91][-5:] [70, 59, 83, 26, 91] 30. [80, 62][1:2] [62] 31.[83, 81, 100, 51, 69, 38, 24, 74, 29, 61, 87, 79, 72][10:14] [87, 79, 72] 31. slice(10,14,1) or [10:14:1] [87, 79, 72] 39.[34, 54, 18, 42, 53][-2:] [42, 53] 39. slice(-2,None,-2) or [-2::-2] [42, 54] 41. [99, 49, 14][-2:] [49, 14] 42. [18, 35, 33, 19, 63, 69, 77, 68, 47, 63, 69, 99][-3:] [63, 69, 99] 45. [90, 52, 10, 15, 42, 43, 32, 39] slice(2,None,4) or [2::4] [10, 32] 48. [45, 23, 57, 60, 11, 10, 66, 57, 27, 30, 19] slice(8,None,1) or [8::1] [27, 30, 19] 55. [37, 15, 31, 66, 77][4:] [77] 57. [94, 11, 72, 87] slice(3,None,-1) or [3::-1] [87, 72, 11, 94] 58.[50, 78, 100, 14, 34, 30, 25, 24, 53, 73, 57][8:] [53, 73, 57] 58. slice(8,None,-2) or [8::-2] [53, 25, 34, 100, 50] 59. [95, 73, 62, 71, 88, 41, 83][:0] [] 60. [100] slice(1,None,-1) or [1::-1] [100] 61.[13, 41, 31, 71, 23, 45, 84, 41, 15][4:] [23, 45, 84, 41, 15] 61. slice(4,None,3) or [4::3] [23, 41] 62.[32, 84, 71][-2:] [84, 71] 62. slice(-2,None,1) or [-2::1] [84, 71] 64.[68, 11, 26][1:] [11, 26] 64. slice(1,None,-1) or [1::-1] [11, 68] 67.[52, 52, 91, 10, 74, 12, 20, 23, 16, 47][-7:] [10, 74, 12, 20, 23, 16, 47] 67. slice(-7,None,1) or [-7::1] [10, 74, 12, 20, 23, 16, 47] 68. [100, 100, 60, 86, 86, 28, 97, 52, 56, 72, 44][-3:] [56, 72, 44] 69. [30, 79, 20, 28, 48, 71, 81, 57, 19, 16, 34, 94][0:-13] [] 70.[41, 53, 13, 59, 39, 31][2:] [13, 59, 39, 31] 70. slice(2,None,1) or [2::1] [13, 59, 39, 31] 71. [90, 86, 50, 96, 90, 81][3:] [96, 90, 81] 72.[66, 23, 63, 92, 51, 24, 16, 34, 59, 56, 21, 19][-5:] [34, 59, 56, 21, 19] 72. slice(-5,None,1) or [-5::1] [34, 59, 56, 21, 19] 74.[58, 59, 57, 92, 96, 91, 74, 24, 36, 83, 43, 88][0:-3] [58, 59, 57, 92, 96, 91, 74, 24, 36] 74. slice(None,-3,-1) or [0:-3:-1] [88, 43] 77.[85, 26, 74, 85, 39, 77, 98][1:] [26, 74, 85, 39, 77, 98] 77. slice(1,None,2) or [1::2] [26, 85, 77] ```