get() can "get the value" based on the key.
grammatical
( key, value )
parameters
- key : (Required) Specify the key to be searched.
- value : (optional) if the key does not exist, return the specified content
return value
- If the key exists, return the value corresponding to the key
- If the key does not exist, return the specified content or None
Example: Getting a dictionary value based on a key
dict1 = {'key1': 'value1', 'key2': 'value2'}
print(('key1'))Output:
value1
1、Set the default return value
get() can specify a "default" "return value". When the key does not exist, it will not report an error, but return a default value, which has the advantage that the program will not have an exception at runtime.
"If the key does not exist, the default return value is None.
dict1 = {'key1': 'value1', 'key2': 'value2'}
print(('key3'))
print(('key3', None))Output:
None
None
"If the key does not exist, the return value will be specified.
dict1 = {'key1': 'value1', 'key2': 'value2'}
print(('key3', 'Specify return value'))Output:
Specify the return value
The return value can be of various data types such as integer, string, tuple, list, etc.
dict1 = {'key1': 'value1', 'key2': 'value2'}
print(('key3', 1))
print(('key3', 1.1))
print(('key3', True))
print(('key3', [1, 2]))
print(('key3', (1, 2)))
print(('key3', {1, 2}))Output:
1
1.1
True
[1, 2]
(1, 2)
{1, 2}
2、嵌套字典取值
dictionary「nested」dictionary time，Can be called multiple times get() ，take a value。
dict1 = {'key1': 'value1', 'key2': {'key3': 'value3'}}
print(('key2').get('key3'))
# Equivalent to this
result = ('key2')
print(result)
result1 = ('key3')
print(result1)Output:
value3
{'key3': 'value3'}
value3
3, get() and dict[key] difference
Both get() and dict[key] can get the value of a dictionary based on the key, the difference being that the
If the key of get() does not exist in the dictionary, it returns "None" or "specified content".
dict1 = {'key1': 'value1', 'key2': 'value2'}
print(('key3'))
print(('key3', 'Specified content'))Output:
None
Specify the content
If the key of dict[key] does not exist in the dictionary, it will "report an error" KeyError: 'key3'
dict1 = {'key1': 'value1', 'key2': 'value2'}
print(dict1['key3'])Output:
4. Statistical element counting
get() counts the number of occurrences of a list element and saves the result to a dictionary.
dict1 = {}
list1 = ['￥', '￥', '￥', '$', '$', '$', '$', '$']
for i in list1:
dict1[i] = (i, 0) + 1
print(dict1)Output:
{'￥': 3, '$': 5}
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