LIST IN PYTHON - 14TH AUG

 LIST IN PYTHON

BEGINNERS PRACTICE QUESTIONS

1. Creating List by accepting data from user

List1=[] #Empty list

n=int(input("Enter number of elements"))   

i=0

while i < n:

    num= int(input("Enter element " + str(i) + ": "))

    List1+=[num]  

    i+=1

print(List1)

OR

#Creating List by accepting data from user

List1=[ ]

n=int(input("Enter number of elements"))  

i=0

while i < n:

    List1+=[int(input("Enter the element"))]  

    i+=1

    print(List1)

2.Write a program to input the size and the list of elements from user. Count the number of elements which are divisible by 5

list1= [ ]

s =int (input("Enter no of elements"))

for i in range(s):

    list1 += [int (input("Enter the Elements"))]

count=0

for num in list1:

        if num % 5 ==0:

            count = count+1

print("No. of elements divisible by 5--",count)

3. Write a program to input the size and the list of elements from user. Count the number of odd, even and zero .

list1 = []

s = int (input("Enter no of Elements:"))

ectr = octr = zctr = 0

for i in range(s):

list1 += [int (input("Enter the Element:"))]

for num in list1:

    if num==0:

       zctr+= 1

    elif num % 2 ==0:

        ectr += 1

    else:

        octr +=1

print("No. of odd, even and zero are:",octr,ectr,zctr)

4. Write a program to input the size and the list of elements from user Count the number of positive, negative and zero

5. Write a program to input a number and a list from user. Count the occurrence of that number in the list.

Sol:

list1=[]

s = int(input("Enter no of elements"))

for i in range(s):

    num= int(input("Enter element " + str(i) + ": "))

    list1 += [num]

n = eval(input("enter number"))

count=0

for i in list1:

    if n==i:

        count=count+1

    if count==0:

        print("element not present")

    else:

print( n ," is present" , count," times")

6.#Find Max number in a given list

list=[1,20,30,87,34]

max = list[0]

for a in list:

    if a > max:    

        max = a

    print(max) 

Traversing using for loop [ Examples]

1.Traversing using for loop Using in operator When 'in' operator is used with for loop, Python access each element of a list in sequence:

list = [12,10,”Python]

for i in list:

    print(i)

2. Traversing using for loop

Using range( )

The sequence of numbers generated by range() can be used as the index to access each element.

Example

list = [12,10,"Python"]

for i in range(3):

        print(list[i])

3.Traversing using while loop

Example

list = [12,10,"Python"]

Index = 0

while Index < 3:

    print(list[Index])

    Index +=1

7.#Program to input a list and to count number of  non-numeric data in a list

list=[]

s = int(input("Enter no of elements - "))  

for i in range(s):

    list+=[eval(input("Enter the element - "))]  

print(list)

ctr=0

for i in range(s):

    if type(list[i])==str:

           ctr+=1

print("no. of non-numeric data - ",ctr)

8.Write a program to input a list. Replace all positive numbers with twice it’s value and all negative numbers with half of it’s value.

list1=[]

s =int(input("Enter no of Elements:"))# Get the number of elements

for i in range(s):

    list1+=[int(input("Enter the elements:"))] # Add each element to the list

for i in range(s): #traversing the list

    if list1[i] < 0:

        list1[i] /=2# Halve the negative numbers

    elif list1[i] > 0:

        list1[i] *= 2# Double the positive numbers

print(list1)

9.#swap the first and last element in the list

sl = [10, 7, 12,66 ,88,77,56, 3, 14]

sl[0], sl[-1] = sl[-1], sl[0]

print(sl)

#or

sl = [10, 7, 12,66 ,88,77,56, 3, 14]

n = len(sl)

# Swapping 

temp = sl[0]

sl[0] = sl[n - 1]

sl[n - 1] = temp

print(sl)

10.#Largest element in list

list = [10, 7, 12,66 ,88,77,56, 3, 14]

large=list[0]

for i in list:

        if i>large:

            large=i

print("Largest number is :",large)

11.#PROGRAM TO CALCULATE MEAN OF A GIVEN LIST NUMBERS

list1=eval(input("Enter the List elements"))

length=len(list1)

mean=sum=0

for i in range(0,length):

    sum+=list1[i]

mean=sum/length

print("Given List is:",list1)

print("Mean of Given List is:",mean)

12.#ADDITION OF ELEMENTS

list1=[4,5,6,6]

list2=[1,2,3,4]

print("ORIGINAL LIST1 IS:"+str(list1))

print("ORIGINAL LIST2 IS:",list2)

res_list=[]

for i in range(0, len(list1)):

    res_list.append(list1[i]+list2[i])

    print(list1[i],list2[i])

print("The resultant List is :"+str(res_list))

13.#LINEAR SEARCH/search for an element in a given list

list1=eval(input("Enter the List elements"))

length=len(list1)

element=int(input("Enter the element to be searched for")) 

for i in range(0,length):

    if element==list1[i]:

        print("Element found At Index:",i)

        break

else:

    print(element,"Not present in the list")

14.#swap the first 3 and last 3 elements 

l1 = []

s = int(input("Enter no. of elements:"))

for i in range(s):

l1.append(int(input("Enter element"+str(i+1)+":")))

print(l1)

l1[:3], l1[-3:] = l1[-3:],l1[:3]

print(l1)

15. #swap the first and last element in the list

sl = [10, 7, 12,66 ,88,77,56, 3, 14]

sl[0], sl[-1] = sl[-1], sl[0]

print(sl)