# Dictionary

Normally, when we want to store the data in list and use index for data access.

However, dict is similar to list but it uses key insteads of index.

TIP

list uses index (number) for data access.

dict uses key (string) for data access.

# Review List

a_list = ["Hello", 1, 2, "World"]
a_list[0]
a_list[1]
a_list[2]
a_list[3]

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# Using Dict

dict_a = {"word":"Hello","number":1}
dict_b = {"k1":1,
          "k2":2}

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# data access

dict_a = {"word":"Hello","number":1}
dict_b = {"k1":1,
          "k2":2}

print(dict_a["word"])
print(dict_a["number"])
dict_b["k2"] = dict_a["number"] + dict_b["k2"]
print(dict_b)

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OUTPUT

Hello
1
{'k1': 1, 'k2': 3}

dict_a = {"k1":1,
          "k2":50,
          "k3":"Hello"}

for k in dict_a:
    print(f"key is {k}, value is {dict_a[k]}")

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OUTPUT

key is k1, value is 1
key is k2, value is 50
key is k3, value is Hello

# add new key and value

dict_a = {"k1":1,
          "k2":50,
          "k3":"Hello"}
dict_a["k4"] = "World"
print(dict_a)

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OUTPUT

{'k1': 1, 'k2': 50, 'k3': 'Hello', 'k4': 'World'}

# del

dict_a = {"k1":1,
          "k2":50,
          "k3":"Hello"}
dict_a["k4"] = "World"
del dict_a["k2"] 
print(dict_a)

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OUTPUT

{'k1': 1, 'k3': 'Hello', 'k4': 'World'}

# in

in is used for checking the key.

dict_a = {"k1":1,
          "k2":50,
          "k3":"Hello"}
print("k1" in dict_a)
print("Hello" in dict_a)

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OUTPUT

True
False