datatype-dictionary (en)

A dictionary stores data as key:value pairs — you look up a value by its key. Here are 5 examples: basic lookup, looping over items (.items()), a list value, turning keys into a list (list(dict.keys())), and using _ as the key name.

Example 1: create a dict and read by key #

dict1={"key1":"john", "key2":"paul"}
print (dict1["key1"])

output:

john

Example 2: loop over key and value (.items()) #

my_dict = {'apple': 3, 'banana': 5, 'orange': 2}

for key, value in my_dict.items():
    print(f'{key} : {value}')

output:

apple : 3
banana : 5
orange : 2

Example 3: value is a list #

dictStu = {'StuName': ['Ada, Billy, Cindy'], 'ChiScore': [10,20,30]}
for key in dictStu:
    print(f'{key}: {dictStu[key]}')

output:

StuName: ['Ada, Billy, Cindy']
ChiScore: [10, 20, 30]

Example 4: turn keys into a list (list(dict.keys())) #

dictStu = {'StuName': 'Ada',
           'ChiScore': 'A'}
keys = list(dictStu.keys())
print(keys)

count=0
while (count<len(keys)):
    print (f'{keys[count]}:{dictStu[keys[count]]}')
    count=count+1

output:

['StuName', 'ChiScore']
StuName:Ada
ChiScore:A

Example 5: use _ as the key name #

dict1 = {'aaa':111, 'bbb':222, 'ccc':333}
for _, value in dict1.items():
    print (f'key={_}, value={value}')

output:

key=aaa, value=111
key=bbb, value=222
key=ccc, value=333