UPDATING PYTHON DICTIONARIES

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INTRODUCTIONS

Like inserting new items in the dictionary, we can modify the dictionaries as well.

Updating existing dictionary value

# UPDATING PYTHON DICTIONARIES
# Example 1


dict_class_wise_count = {'A':100, 'B':200, 'C':300, 'D':400, 'E':500}
print("\nList of key value pair of dict_class_wise_count ->", dict_class_wise_count)

dict_class_wise_count['E'] = 600

print("\nList of key value pair of dict_class_wise_count ->", dict_class_wise_count)

UPDATING PYTHON DICTIONARIES : Output

List of key value pair of dict_class_wise_count -> {'A': 100, 'B': 200, 'C': 300, 'D': 400, 'E': 500}

List of key value pair of dict_class_wise_count -> {'A': 100, 'B': 200, 'C': 300, 'D': 400, 'E': 600}

In the above example, we have updated the value of key “E“.

# UPDATING PYTHON DICTIONARIES
# Example 2


dict_class_wise_count = {'A':100, 'B':200, 'C':300, 'D':400, 'E':500}
print("\nList of key value pair of dict_class_wise_count ->", dict_class_wise_count)

dict_class_wise_count['B'] = 1200
dict_class_wise_count['C'] = dict_class_wise_count['C']*6

print("\nList of key value pair of dict_class_wise_count ->", dict_class_wise_count)

UPDATING PYTHON DICTIONARIES : Output

List of key value pair of dict_class_wise_count -> {'A': 100, 'B': 200, 'C': 300, 'D': 400, 'E': 500}

List of key value pair of dict_class_wise_count -> {'A': 100, 'B': 1200, 'C': 1800, 'D': 400, 'E': 500}

In the above example, we have modified the values against keys B and C.

# UPDATING PYTHON DICTIONARIES
# Example 3


dict_class_wise_count = {'A':100, 'B':200, 'C':300, 'D':400, 'E':500}
print("\nList of key value pair of dict_class_wise_count ->", dict_class_wise_count)

dict_class_wise_count['E'] = [500, 501, 502]

print("\nList of key value pair of dict_class_wise_count ->", dict_class_wise_count)

UPDATING PYTHON DICTIONARIES : Output

List of key value pair of dict_class_wise_count -> {'A': 100, 'B': 200, 'C': 300, 'D': 400, 'E': 500}

List of key value pair of dict_class_wise_count -> {'A': 100, 'B': 200, 'C': 300, 'D': 400, 'E': [500, 501, 502]}

In the above example, we have updated the value against key “E” with a list item.

Adding new dictionary value against existing key

# UPDATING PYTHON DICTIONARIES
# Example 4

dict_class_wise_count = {'A':100, 'B':200, 'C':300, 'D':400, 'E':[500, 501, 502]}
print("\nList of key value pair of dict_class_wise_count ->", dict_class_wise_count)

dict_class_wise_count['E'].append(503)

print("\nList of key value pair of dict_class_wise_count ->", dict_class_wise_count)

UPDATING PYTHON DICTIONARIES : Output

List of key value pair of dict_class_wise_count -> {'A': 100, 'B': 200, 'C': 300, 'D': 400, 'E': [500, 501, 502]}

List of key value pair of dict_class_wise_count -> {'A': 100, 'B': 200, 'C': 300, 'D': 400, 'E': [500, 501, 502, 503]}

In the above example, we have used a list item against the key “E“. Then we have added a new element 503 inside the list.

# UPDATING PYTHON DICTIONARIES
# Example 5

dict_class_wise_prog = {'A':'Python', 'B':'Java', 'C':'C++'}
print("\nList of key value pair of dict_class_wise_prog ->", dict_class_wise_prog)

dict_class_wise_prog['C'] = {'C1':'PHP', 'C2':'XML'}

print("\nList of key value pair of dict_class_wise_prog ->", dict_class_wise_prog)

UPDATING PYTHON DICTIONARIES : Output

List of key value pair of dict_class_wise_prog -> {'A': 'Python', 'B': 'Java', 'C': 'C++'}

List of key value pair of dict_class_wise_prog -> {'A': 'Python', 'B': 'Java', 'C': {'C1': 'PHP', 'C2': 'XML'}}

In the above example, we have updated the value against the key “C” with a dictionary.

update() method

update() method is used to update an existing dictionary
It can update the value against an existing key or it can add new key value pair

Updating an existing dictionary value

# UPDATING PYTHON DICTIONARIES
# Example 6

dict_class_wise_prog = {'A':'Python', 'B':'Java', 'C':'C++'}
print("\nList of key value pair of dict_class_wise_prog ->", dict_class_wise_prog)

dict_class_wise_prog.update({'C':'PHP'})

print("\nList of key value pair of dict_class_wise_prog ->", dict_class_wise_prog)

UPDATING PYTHON DICTIONARIES : Output

List of key value pair of dict_class_wise_prog -> {'A': 'Python', 'B': 'Java', 'C': 'C++'}

List of key value pair of dict_class_wise_prog -> {'A': 'Python', 'B': 'Java', 'C': 'PHP'}

In the above example, we have updated the value against key “C“.

Adding new key value pair

# UPDATING PYTHON DICTIONARIES
# Example 7

dict_class_wise_prog = {'A':'Python', 'B':'Java', 'C':'C++'}
print("\nList of key value pair of dict_class_wise_prog ->", dict_class_wise_prog)

dict_class_wise_prog.update({'D':'PHP', 'E':'XML'})

print("\nList of key value pair of dict_class_wise_prog ->", dict_class_wise_prog)

UPDATING PYTHON DICTIONARIES : Output

List of key value pair of dict_class_wise_prog -> {'A': 'Python', 'B': 'Java', 'C': 'C++'}

List of key value pair of dict_class_wise_prog -> {'A': 'Python', 'B': 'Java', 'C': 'C++', 'D': 'PHP', 'E': 'XML'}

In the above example, we have added two new key value pair.

# UPDATING PYTHON DICTIONARIES
# Example 8

dict_class_wise_prog = {'A':'Python', 'B':'Java', 'C':'C++'}
print("\nList of key value pair of dict_class_wise_prog ->", dict_class_wise_prog)

dict_class_wise_prog.update({'D':'PHP', 'E':'XML'})
dict_class_wise_prog_copy = dict_class_wise_prog;

print("\nList of key value pair of dict_class_wise_prog ->", dict_class_wise_prog)
print("\nList of key value pair of dict_class_wise_prog_copy ->", dict_class_wise_prog_copy)

UPDATING PYTHON DICTIONARIES : Output

List of key value pair of dict_class_wise_prog -> {'A': 'Python', 'B': 'Java', 'C': 'C++'}

List of key value pair of dict_class_wise_prog -> {'A': 'Python', 'B': 'Java', 'C': 'C++', 'D': 'PHP', 'E': 'XML'}

List of key value pair of dict_class_wise_prog_copy -> {'A': 'Python', 'B': 'Java', 'C': 'C++', 'D': 'PHP', 'E': 'XML'}

In the above example, we have added two new key value pair and then we have created a new dictionary based on existing dictionary.

Using operator**

** operator helps us to merge one dictionary data into other dictionary along with additional items.

# UPDATING PYTHON DICTIONARIES
# Example 9

dict_class_wise_prog = {'A':'Python', 'B':'Java', 'C':'C++'}
print("\nList of key value pair of dict_class_wise_prog ->", dict_class_wise_prog)


dict_class_wise_prog_copy = {**dict_class_wise_prog, **{'D':'PHP', 'E':'XML'}}

print("\nList of key value pair of dict_class_wise_prog ->", dict_class_wise_prog)
print("\nList of key value pair of dict_class_wise_prog_copy ->", dict_class_wise_prog_copy)

UPDATING PYTHON DICTIONARIES : Output

List of key value pair of dict_class_wise_prog -> {'A': 'Python', 'B': 'Java', 'C': 'C++'}

List of key value pair of dict_class_wise_prog -> {'A': 'Python', 'B': 'Java', 'C': 'C++'}

List of key value pair of dict_class_wise_prog_copy -> {'A': 'Python', 'B': 'Java', 'C': 'C++', 'D': 'PHP', 'E': 'XML'}

In the above example, we have used the ** operator use create and new dictionary dict_class_wise_prog_copy from dict_class_wise_prog along with two new key value pair.

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