Dictionary in Python

1) Dictionary Concept in Python:-

Using this we can store elements using key=>value pair, the key is used to provide identity, and value is used to store data.

For example, if we store five different student records then rollno will work as a key, and  1001  will work as a value.

Syntax of the dictionary:-

var = {key:value,key:value,...}

Stu = {"rno":1001,"sname":"manish kumar","branch":"CS","fees":45000}
rno,sname,branch and fees is the key and 1001,"manish kumar","cs",45000 is the values
................................................................................................................................................................
It will display records based on proper sequence, It is an enhancement of set object.
It provides better search and performance as compared to LIST Object.
Dictionary provides a mutable object that means we can add, edit and delete Dictionary Elements Dynamically.
Program to display the only key on the Dictionary:-

x = {"rno":1001,"sname":"manish kumar", "branch":"cs", "fees":15000}

for key in x:

    print(key)

 Program to display the only value on the Dictionary:-

x = {"rno":1001,"sname":"manish kumar", "branch":"cs", "fees":15000}

for key in x:

    print(x[key])

 Program to display the key and value both on the Dictionary:-

1)

x = {"rno":1001,"sname":"manish kumar", "branch":"cs", "fees":15000}

for key in x:

    print(key,x[key])

 2)

for k,v in student.items():

      print(k, ' ',v)

Dictionary provides mutable Object because we can modify(add, edit and delete) dictionary objects?

Example of Dictionary to add, edit and delete elements

x = {"rno":1001,"sname":"manish kumar", "branch":"cs", "fees":15000}

x["rno"]=1002   #modify value

del x["rno"]    #delete key

x.update({'sem':'3rd'}) # append dictionary

for key in x:

    print(key,x[key])

   

How to take input from users in dictionary Objects?

x = {}

item = int(input("enter number of items in dictionary"))

for i in range(0,item):

    key = input("enter key")

    value = input("enter value")

    x.update({key:value})

print(x)    

WAP to reverse of Dictionary Elements:-

stu = {"rno":1001,"sname":"manish kumar","branch":"CS","fees":45000}
stu["rno"]=1002
del stu["rno"]
stu.update({"fees":55000})
stu.update({"sem":"vth"})
l = []
for k in stu:
   print("key is ",k ," and value is ",stu[k])
   l.append(k)
for i in range(len(l)-1,-1,-1):
   print("key is ",l[i] ," and value is ",stu[l[i]])

WAP to display dictionary elements in reverse on dictionary format:-

s = {"empid":"Kang1001","empid":"Kang1001","empname":"jay kumar","deptname":"Sales","Salary":45000}

key=[]

val=[]

for d in s:

    key.append(d)

    val.append(s[d])

res= "{"

for i in range(len(key)-1,-1,-1):

   if i!=0: 

    res= res + str(key[i]) + ":" + str(val[i])+","

   else:

    res= res + str(key[i]) + ":" + str(val[i])   

res= res+ "}"

print(res)

for data in s:

    print(data,s[data])

WAP to find max elements in Dictionary?

WAP to find the max key in Dictionary?

Answer:-

d = {"A":12,"C":34,"B":11,"E":78,"F":22}

m =0

for item in d:

    if m<d[item]:

        m=d[item]

print("max value is ",m)        

WAP to convert a dictionary to set?