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)
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