list python notes.txt

delete list element - used to delete emelemt of list or delete variables

del a - delete complete list
  or
del a[2] - list element
 or
del a[2,5]  range in list 



list opreators

1] list repeater - repetation of list  --multiply content of list 

syntax - list*no of times repeation

example	
a=[11,22,33]
print (a*3)

>>> [11,22,33,11,22,33,11,22,33]    

2] list concationation  used to merge /concate 2 or more list 
	+ symbol is used to concate 2 list

syntax list1+list2

example

a=[11,22]
b=[33,44,55]
print(a+b)

>>> [11,22,33,44,55]

3]  display list elements one by one 
	we use for loop here 
	syntax  
	
	for value in list:
		print(value)	

example
	a=[11,22,33,44]
	for i in a:
		print(i)
>>>
11
22
33
44


 for loop syntax
for variable in range(start_index, end_index)

example
for a in range(1,5)
	print(a)
>>>
1
2
3
4
5

or 

for variable in listname
	print(variable)

a=[11,22,33,44]
	for i in a:
		print(i)

>>>
11
22
33
44

s=["java","php","cpp","dsa","python"]
for i in s:
   print(i)

>>>

java
php
cpp
dsa
python



Q) accept no number in list and print

n=int(input("ENter number"))
a=[]
for i in range(0,n):
	num=int(input("ENter number"))
	a.append(num)
print(a)
print("Even numbers")
for i in range(0,n):
	if a[i]%2==0:
		print(a[i])


# append --add only one element at the end of list

a=[11,22,33,44]
b=[10,20,30]
a.append(b)
print(a)

output >>> [11,22,33,44,[10,20,30]]

# extend -- add more than one element at the end of list 

a=[11,22,33,44]
b=[10,20,30]
a.extend(b)
print(a)

output >>> [11,22,33,44,10,20,30]

# insert - this function insert element at given potion in the list

syntax -- a.insert(index,no_to insert)

example

a=[11,22,33,44]
a.insert(2,99)
print(a)

output >>> [11,22,99,33,44]

# remove - remove the first occurred element of the element is remove 
if there are same value more than one times

del is used to remove element by insex
del a[2]

remove is used to remove element by value


a=[11,22,33,44,55,33]
a.remove(33)
print(a)

>>>[11,22,44,55,33]   ---only first element is removed in case there 
are  multiple nos\values


# pop()

it is used tu remove and retrive last element

syntax val=a.pop()

example
a=[11,22,33,44]
val=a.pop()
print("a=",a)
print("Deleted /pop element ",val)

>>> a= [11,22,33]
>>> deleted elemment=44

--by default pop function remove last element 
--if we pass index to pop function we can retrive any index element

syntax val=a.pop(index)

example
a=[11,22,33,44]
val=a.pop(2)
print(a)
print("Deleted /pop element ",val)

>>> a= [11,22,44]
>>> deleted elemment=33


#revere()  -- it is uued to reverse the list element

syntax a.reverse()

a=[11,22,33,44]
a.reverse()
print(a)

>>> [44,33,22,11]

# len() --it is used to print length of list

a=[11,22,33,44,33,55,33]
print("Length of list=",len(a))

>>> Length of list = 7

# count --used to count how many times the no is in the list

a=[11,22,33,44,33,55,33]
print("Count Value=",count(33))

>>> Count value = 3


max and min -- used to display max and min element
a=[11,22,33,44,7,33,55,33]

print("minimum number=",min(a))
print("maximun number=",max(a))



# sort -- used to sort element in accending order

syntax a.sort()

a=[66,44,11,9,66,77,44]
a.sort()
print(a)

>>>[9,11,44,44,66,66,77]

# sort reverse-- used to sort element in descending order

syntax a.sort(reverse=True)

a=[66,44,11,9,66,77,44]
a.sort(reverse=True)
print(a)

>>>[77,66,66,44,44,11,9]

# clear()-- used to empty / clear the list
a=[11,22,33]
a.clear()
print(a)

>>>[]


# copy() -- return shallow copy of the list
	-- copy one list in another
a=[11,22,33]
b=a.copy()
print(a)
print(b)

>>>> [11,22,33]		--a list
>>>> [11,22,33]		--b list