Python – 更新字典列表的值

在本文中，我们将更新字典列表的值。

方法一：使用 append()函数

append函数用于在字典列表中插入一个新值，我们将使用 pop()函数来消除重复数据。

Syntax:

• dictionary[row][‘key’].append(‘value’)
• dictionary[row][‘key’].pop(position)

Where:

• dictionary is the input list of dictionaries
• row is the row that we want to update
• value is the new value to be updated
• key is the column to be updated
• position is the place where the old value is there

用于创建字典列表的Python程序

Python3

# create a list of dictionaries
# with student data
data = [
    {'name': 'sravan', 'subjects': ['java', 'python']},
    {'name': 'bobby', 'subjects': ['c/cpp', 'java']},
    {'name': 'ojsawi', 'subjects': ['iot', 'cloud']},
    {'name': 'rohith', 'subjects': ['php', 'os']},
    {'name': 'gnanesh', 'subjects': ['html', 'sql']}
]
  
# display first student
print(data[0])
  
# display all student
data

输出：

{'name': 'sravan', 'subjects': ['java', 'python']}
[{'name': 'sravan', 'subjects': ['java', 'python']},
 {'name': 'bobby', 'subjects': ['c/cpp', 'java']},
 {'name': 'ojsawi', 'subjects': ['iot', 'cloud']},
 {'name': 'rohith', 'subjects': ['php', 'os']},
 {'name': 'gnanesh', 'subjects': ['html', 'sql']}]

更新上述字典列表中的值

Python3

# update first student python subject
# to html
data[0]['subjects'].append('html')
data[0]['subjects'].pop(1)
  
# update third student java subject
# to dbms
data[2]['subjects'].append('dbms')
data[2]['subjects'].pop(1)
  
# update forth student php subject
# to php-mysql
data[3]['subjects'].append('php-mysql')
data[3]['subjects'].pop(0)
  
# display updated list
data

输出：

[{'name': 'sravan', 'subjects': ['java', 'html']},
 {'name': 'bobby', 'subjects': ['c/cpp', 'java']},
 {'name': 'ojsawi', 'subjects': ['iot', 'dbms']},
 {'name': 'rohith', 'subjects': ['os', 'php-mysql']},
 {'name': 'gnanesh', 'subjects': ['html', 'sql']}]

方法二：使用 insert()函数

该函数用于根据索引插入更新的数据。

Syntax:

• dictionary[row][‘key’].insert(index,’value’)
• dictionary[row][‘key’].pop(position)

Where,

• dictionary is the input list of dictionaries
• row is the row that we want to update
• value is the new value to be updated
• index is the position to be updated
• key is the column to be updated
• position is the place where the old value is there

示例：用于更新字典列表中的值的Python程序

Python3

# update first student python subject
# to html
data[0]['subjects'].insert(0, 'html')
data[0]['subjects'].pop(1)
  
# update third student java subject
# to dbms
data[2]['subjects'].insert(0, 'dbms')
data[2]['subjects'].pop(1)
  
# update forth student php subject
# to php-mysql
data[3]['subjects'].insert(1, 'php-mysql')
data[3]['subjects'].pop(0)
  
# display updated list
data

输出：

[{'name': 'sravan', 'subjects': ['html', 'python']},
 {'name': 'bobby', 'subjects': ['c/cpp', 'java']},
 {'name': 'ojsawi', 'subjects': ['dbms', 'cloud']},
 {'name': 'rohith', 'subjects': ['php-mysql', 'os']},
 {'name': 'gnanesh', 'subjects': ['html', 'sql']}]