> For the complete documentation index, see [llms.txt](https://0xa1mn.gitbook.io/cyber-explained/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://0xa1mn.gitbook.io/cyber-explained/programming/python/hello-world/lists-tuple-sets-and-dictionaries.md). # Lists, Tuple, Sets and Dictionaries ### Differences | **Lists** | **Tuples** | **Sets** | **Dictionaries** | | ----------------------------------------- | ------------------------------------------- | ---------------------------------------------------- | -------------------------------------------------------------------------------------- | | A list is a collection of *ordered* data. | A tuple is an *ordered* collection of data. | A set is an *unordered* collection. | A dictionary is an *unordered* collection of data that stores data in key-value pairs. | | Lists are *mutable*. | Tuples are *immutable*. | Sets are *mutable* and have *no duplicate elements*. | Dictionaries are mutable and keys do not allow duplicates. | | Lists are declared with square braces. | Tuples are enclosed within parenthesis. | Sets are represented in curly brackets. | Dictionaries are enclosed in curly brackets in the form of key-value pairs. | ### Lists #### How to create ``` list1=[1,4,"Gitam",6,"college"] list2=[] # creates an empty list list3=list((1,2,3)) print(list1) print(list2) print(list3) ``` #### Operations on Lists ``` list1=["hello",1,4,8,"good"] print(list1) list1[0]="morning" # assigning values ("hello" is replaced with "morning") print(list1) print(list1[4]) print(list1[-1]) # list also allow negative indexing print(list1[1:4]) # slicing list2=["apple","mango","banana"] print(list1+list2) # list concatenation ``` #### Add and Remove items The `append()` method adds a single item at the end of the list without modifying the original list. The `pop()` method removes the item at the given index from the list and returns it. ``` list1=["apple","banana","grapes"] list1.append("strawberry") # strawberry is added to the list print(list1) list1.pop() # removes the last element from the list print(list1) list1.pop() print(list1) ``` #### Sort Items The `sort()` method sorts the elements of a given list in a specific ascending or descending order. #### Find Items `index()` searches for a given element from the start of the list and returns the lowest index where the element appears. #### Count The `count()` method returns the number of times the specified element appears in the list. #### Reverse The `reverse()` method reverses the elements of the list. ### Tuple #### How to create ``` tuple1=(1,2,"college",9) tuple2=() # creates an empty tuple tuple3=tuple((1,3,5,9,"hello")) print(tuple1) print(tuple2) print(tuple3) ``` #### Operations on Tuples ``` tuple1=("good",1,2,3,"morning") print(tuple1) print(tuple1[0]) # accessing values using indexing #tuple1[1]="change" # a value cannot be changed as they are immutable tuple2=("orange","grapes") print(tuple1+tuple2) # tuples can be concatenated tuple3=(1,2,3) print(type(tuple3)) ``` #### Add and Remove items An element cannot be added to the tuple as it is immutable. ``` tuple1=(1,2,3,4) # tuple1.pop() tuple cannot be modified # tuple1.append() tuple cannot be modified print(tuple1) ``` #### Sort Item Though tuples are ordered, the elements cannot be sorted. #### Find Items Searches the tuple for a specified value and returns the position of where it was found. #### Count The `count()` method returns the number of times a specified value occurs in a tuple. #### Reverse The `reverse()` method is not defined in tuples, as they are unchangeable ### Sets #### How to create ``` set1={1,2,3,4,5,"hello","tup"} set2={(1,8,"python",7)} print(set1) print(set2) ``` #### Operations on Sets ``` set1={1,2,3,4,5} print(set1) # set1[0] sets are unordered, so it doesnot support indexing set2={3,7,1,6,1} # sets doesnot allow duplicate values print(set2) ``` #### Add and Remove items The set `add()` method adds a given element to a set. The `pop()` method removes a random item from the set. ``` set1={"water","air","food"} set1.add("shelter") # adds an element to the set at random position print(set1) set1.add("clothes") print(set1) set1.pop() # removes random element from the set print(set1) ``` #### Sort Items Elements in the set cannot be sorted as they are unordered. #### Find Items The index of a particular element is not retrieved as they are unordered. #### Count There are no `count()` methods in sets as they do not allow any duplicates. #### Reverse The sets are unordered, which refrains from applying the `reverse()` method. ### Dictionaries #### How to create ``` dict1={"key1":"value1","key2":"value2"} dict2={} # empty dictionary dict3=dict({1:"apple",2:"cherry",3:"strawberry"}) print(dict1) print(dict2) print(dict3) ``` #### Operations on Sets ``` dict1={"key1":1,"key2":"value2",3:"value3"} print(dict1.keys()) # all the keys are printed dict1.values() # all the values are printed dict1["key1"]="replace_one" # value assigned to key1 is replaced print(dict1) print(dict1["key2"]) ``` #### Add and Remove items The `update()` method updates the dictionary with the specified key-value pairs. The `pop()` method removes the specified item from the dictionary. ``` dict1={"fruit1":"apple","fruit2":"banana","veg1":"tomato"} dict1.update({"veg2":"brinjal"}) print(dict1) dict1.update({"veg3":"chilli"}) # updates the dictionary at the end print(dict1) dict1.pop("veg2") print(dict1) ``` #### Sort Items `sorted()` method is used to sort the keys in the dictionary by default. #### Find Items The `get()` method returns the value of the item with the specified key. #### Count The `count()` method is not defined in the dictionary. #### Reverse The elements cannot be reversed, as the items in the dictionary are in the form of key-value pairs