ArrayOperation.md

Array Operations

1.Retrieve element

for Retrieving elements from an array, there are two different ways

1. Single element Retrieval
2. Multiple elements retrieval using slicing.

1. Single Element Retrieval

• A collection of elements each identified by an array index.
• Index start at zero(0) array.Because of the index, random access of elements is possible.
• Use [] parenthesis to retrieve an element from an array
• Array elements can be accessed using positive index start from the first element in the array

like 0,1,2,3,4...

• Array elements also can be accessed using negative indexes which start from ending of the list

like -1,-2,-3,-4..

Syntax:

array_name[index]

Example:

importarraydata=array.array("i",[20,10,15,23])
#for 20 use 0 index to get value from itresult=data[0]
print("Element At 0 Index")
print(result)
#Result:20#Access 20 using negative indexresult=data[-4]
print("\nGet 20 Element Using Negative Index")
print(result)
#Result:20#for 15 use 2 index to get value from itresult=data[2]
print("\nElement At 2nd Index")
print(result)
#Result:15#for 15 using Negative indexresult=data[-2]
print("\nGet element At -2 Index")
print(result)
#Result:15#For outer index result=data[10]
print(result)
#Result Error: array index out of range

Output:

Element At 0 Index
20
Get 20 Element Using Negative Index
20
Element At 2nd Index
15
Get element At -2 Index
15
Traceback (most recent call last):
File "/tmp/sessions/8796c948b36129d7/main.py", line 31, in <module>
result=data[10]
IndexError: array index out of range

2.Multiple Elements using slicing

• In Python, we can easily access a range of items in an array using the slicing operator :

Normal Syntax:

array_name[startindex(including):EndIndex(Excluding)]

Other Syntax :

array_Name[:] >AllElementsarray_name[start:end] >BeginingtoEndarray_name[:end] >Beginingtoendarray_name[start:] >beginingtoend

Examples:

importarraydata=array.array("i",[20,10,15,23])
#ALL Elementsstart=0end=4result=data[start:end]
print("Array From 0 index to till 4 index")
print(result)
#Result:array('i', [20, 10, 15, 23])#Get First 2 Elementsresult=data[:2] #or data[0:2]print("\nGet First 2 Element")
print(result)
#Result:array('i', [20, 10])#Get Last 3 Elementsresult=data[1:] #or data[1:3]print("\nGet Last 3 Element")
print(result)
#Result:array('i', [10, 15, 23])

Output:

Array From 0 index to till 4 index
array('i', [20, 10, 15, 23])
Get First 2 Element
array('i', [20, 10])
Get Last 3 Element
array('i', [10, 15, 23])

2.Add Element

• After the creation of the array, we can add another element to array with the help of following built-in functions

1. append()
2. insert()
3. extend()

1.append()

• append() function add a single element to an array at the end of the array

Syntax:

arrayName.append("element")

Example:

importarraydata=array.array("i",[20,10,15,23])
print("Before append of new Element")
print(data)
#Append 6 to the data arraydata.append(6)
print("After appending element")
print(data)

Output:

Before append of new Element
array('i', [20, 10, 15, 23])
After appending element
array('i', [20, 10, 15, 23, 6])

2.insert()

• append() add elements at only end of the array but if you want to add an element at the specific position then use insert.
• if an element is already present at insertion position then element at insertion position will be shifted to the right side by one.
• If you pass out of range positive index then element should be added at the end of an array.
• If you pass out of range negative index then element should be added at the beginning of an array.

Syntax:

array_name.insert(index,"value")

Example:

importarraydata=array.array("i",[20,10,15,23])
print("Normal Array")
print(data)
#Append 6 at 1th positiondata.insert(1,6)
print("After inserting 6 at first position element")
print(data)

Output:

Normal Array
array('i', [20, 10, 15, 23])'
After inserting 6 at first position element
array('i', [20, 6, 10, 15, 23])

3.extend()

• append() and insert() function add single element to an array to add multiple element to an array or join two different array extend() built in function is is used
• Add several items using extend() method.
• extend() appends iterating to the end of the array

Syntax:

array_name.extend(iterable_object)

iterable_object:list,tuple

Example:

importarraydata=array.array("i",[20,10,15,23])
print("Normal Array")
print(data)
#add [6,11,12] array to data arraydata.extend([6,11,12])
print("\n\n Array After Extending [6,11,12] ")
print(data)

Output:

Normal Array
array('i', [20, 10, 15, 23])
Array After Extending [6,11,12] array('i', [20, 10, 15, 23, 6, 11, 12]) 

3.Update Element

• The array is the mutable object. so elements of an array are changeable

Syntax:

To change or modify an element of an array use index of that element

array_name[index]=value

To modify some range of elements from an array

array_name[startindex:endindex]=value

Example:

importarraydata=array.array("i",[20,10,15,23])
print("Normal Array")
print(data)
#update 20 with 30 and 20 element at 0 indexdata[0]=30print("\nArray after modification of 20 with 30")
print(data)
#Update last 2 element 9 and 12data[-2:]=array.array('i',[9,12])
print("\nArray After updating multiple values")
print(data)

Output:

Normal Array
array('i', [20, 10, 15, 23])
Array after modification of 20 with 30
array('i', [30, 10, 15, 23])
Array After updating multiple values
array('i', [30, 10, 9, 12])

data[0]='h'
This will generate error
Erro:an integer is required (got type str)
data[552]='1'
Error:array assignment index out of range

4. Remove Element

• You can delete a complete array or element there are the following options are available.

1. del
2. pop()
3. remove()

1.del

• We can delete one or more items using python del statement.
• we can also delete a complete array using del keyword.

Syntax:

delete of specific index item

delarray_name[index]

Delete Complete array

delarray_name

Examples:

importarraydata=array.array("i",[20,10,15,23])
print("Normal Array")
print(data)
#Delete the first Element from an arraydeldata[0]
print("\nAfter delete first element")
print(data)
#delete complete arraydeldataprint("\nErrror")
print(data)
#result:name 'data' is not defined

Output:

Normal Array
array('i', [20, 10, 15, 23])
After delete first element
array('i', [10, 15, 23])
Errror
Traceback (most recent call last):
File "/tmp/sessions/139fbf48debb94d3/main.py", line 17, in <module>
print(data)
NameError: name 'data' is not defined

2.pop()

• pop() method used to remove an item at the given index.
• pop() also return an item which is deleted

Syntax:

array_name.pop(index)

Example:

importarray#Normal Arrayarr=array.array('i',[20, 10, 15, 23])
#print Normal Arrayprint("Normal Array")
print(arr)
#Delete last Elementarr.pop()
print("\nAfter Poping Last Element")
#print array after popprint(arr)

Output:

Normal Array
array('i', [20, 10, 15, 23])
After Poping Last Element
array('i', [20, 10, 15])

3.remove()

• We can use the remove() method to remove the given item.
• remove() method accept element instead of the index.
• remove() method removes an element from an array and doesn't return anything
• If the element not found in list remove() gives an error

x not in the list

Syntax:

array_name.remove(elements)

Example:

importarraydata=array.array("i",[20,10,15,23])
print("Normal Array")
print(data)
#Remove 10 from an array using remove()data.remove(10)
print("\nPrint array after remove of 10")
print(data)

Output:

Normal Array
array('i', [20, 10, 15, 23])
Print array after remove of 10
array('i', [20, 15, 23])