javascript 计算每个项目在 JSON 中的出现次数
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Count occurrences of each item in JSON
提问by relyt
I want to return the count of each property. For example, I would like to return how many people are in each group. So for the following JSON, it would return 3 people in Group 1, 3 people in Group 3, 2 people in Group 16, etc.
我想返回每个属性的计数。例如，我想返回每个组中有多少人。因此，对于以下 JSON，它将返回第 1 组中的 3 个人、第 3 组中的 3 个人、第 16 组中的 2 个人，等等。
I'm looking for a Javascript or jQuery solution.
我正在寻找 Javascript 或 jQuery 解决方案。
Note: I do not need help parsing the JSON. I only need help in finding the counts of each occurrence.
注意：我不需要帮助解析 JSON。我只需要帮助查找每次出现的次数。
{
"people":[
{"id":"0","name":"Mike Johnson","group":1},
{"id":"1","name":"Bob Smith","group":2},
{"id":"2","name":"Richard Thomas","group":3},
{"id":"3","name":"Betty White","group":16},
{"id":"4","name":"Tim Thompson","group":3},
{"id":"5","name":"Carl Lewis","group":16},
{"id":"6","name":"Kathy Towers","group":3},
{"id":"7","name":"Billy Bob","group":1},
{"id":"8","name":"Sally Bailey","group":1}
]
}
回答by Ian
Like some comment said, you have to loop through the "people" array. It's easy to turn this "feature" into a function like I have so you can just specify the group you're searching for, and get back the number of people.
就像某些评论所说的那样，您必须遍历“people”数组。很容易将这个“功能”变成像我这样的功能，这样你就可以指定你正在搜索的组，然后找回人数。
var obj = {
"people": [
{"id":"0","name":"Mike Johnson","group":1},
{"id":"1","name":"Bob Smith","group":2},
{"id":"2","name":"Richard Thomas","group":3},
{"id":"3","name":"Betty White","group":16},
{"id":"4","name":"Tim Thompson","group":3},
{"id":"5","name":"Carl Lewis","group":16},
{"id":"6","name":"Kathy Towers","group":3},
{"id":"7","name":"Billy Bob","group":1},
{"id":"8","name":"Sally Bailey","group":1}
]
};
function getCount(group) {
var count = 0;
for (var i = 0; i < obj.people.length; i++) {
if (obj.people[i].group == group) {
count++;
}
}
return count;
}
getCount(1); // should return 3
If objisn't global, you can pass it to the function and it would be like this:
如果obj不是全局的，你可以将它传递给函数，它会是这样的：
function getCount(arr, group) {
var count = 0;
for (var i = 0; i < arr.length; i++) {
if (arr[i].group == group) {
count++;
}
}
return count;
}
getCount(obj.people, 1); // should return 3
回答by Blender
You can extract the groups by using something like this:
您可以使用以下方法提取组：
> var groups = foo['people'].map(function(value, index) {return value['group']});
[1, 2, 3, 16, 3, 16, 3, 1, 1]
From there, just create an object with these keys:
从那里，只需使用这些键创建一个对象：
var group_count = {};
groups.forEach(function(value, index) {
if (value in group_count) {
group_count[value] += 1;
} else {
group_count[value] = 1;
}
});
This will give you an object that contains the number of occurrences of each group.
这将为您提供一个包含每个组出现次数的对象。
Also, this code won't work IE8 and lower, so you'll have to find a forEachand mappolyfill somewhere on the web.
此外，此代码不适用于 IE8 及更低版本，因此您必须在网络上的某处找到一个forEach和mappolyfill。
