Question

我在列表中有一个字典，结构如下：

my_list = [
 {
     "id" : 1,
     "name" : "foo",
     "address" : "here"
 },
 {
     "id" : 2,
     "name" : "foo2",
     "address" : "there"
  },
 {
     "id" : 3,
     "name" : "foo3",
     "address" : "there"
  },
]

如何获取特定地址的总数？比如我想知道有多少人来自地址＆＃34;那里＆＃34;。我该怎么办？

Answer 1

使用len函数和list_comprehension。

>>> my_list = [
 {
     id : 1,
     'name' : 'foo',
     'address' : 'here'
 },
 {
     id : 2,
     'name' : 'foo2',
     'address' : 'there'
  },
 {
     id : 3,
     'name' : 'foo3',
     'address' : 'there'
  },
]
>>> len([x for x in my_list if x['address'] == 'there'])
2

Answer 2

count = 0
for dictionary in my_list:
    if dictionary["address"] == "there":
        count+=1
print count

Answer 3

您可以使用sum函数，如下所示，注意，您需要遍历字典并检查目标键的值是否为there！：

sum(1 for d in my_list if d['address']=='there')

演示：

>>> my_list = [
...  {
...      'id' : 1,
...      'name' : 'foo',
...      'address' : 'here'
...  },
...  {
...      'id' : 2,
...      'name' : 'foo2',
...      'address' : 'there'
...   },
...  {
...      'id' : 3,
...      'name' : 'foo3',
...      'address' : 'there'
...   },
... ]
>>> sum(1 for d in my_list if d['address']=='there')
2

Answer 4

您可以使用collections.Counter和列表推导

>>> from collections import Counter
>>> d = Counter([addr["address"] for addr in my_list])
>>> d["there"]
2

Answer 5

如果某些条目可能缺少address字段，您可以使用.get()方法。

sum(x.get('address') == "there" for x in my_list)

根据字典值计算列表中字典中的项目数

5 个答案: