int i = 0;
while(true) {
std::thread t1(function1);
std::thread t2(function2);
t1.detach();
t2.detach();
//also break your infinite loop here
if( ++i < 4)
break;
}
我有上面的数组,我必须构建对象,基于&#34;类型&#34;价值即&#34;预定义&#34;或&#34; custom&#34;如下
var json = [{
"city": "California",
"name": "Joe",
"age": 17,
"type",:"custom"
}, {
"city": "California",
"name": "Bob",
"age": 17,
"type",:"predefined"
}, {
"city": "California",
"name": "Bob",
"age": 35,
"type",:"custom"
}, {
"city": "Texas",
"name": "Bob",
"age": 35,
"type",:"custom"
}, {
"city": "Florida",
"name": "Bob",
"age": 35,
"type",:"predefined"
}];
任何使用javascript或lodash的方法
答案 0 :(得分:0)
您可以使用array.reduce创建包含聚合数据的新对象。例如:
const result = json.reduce((obj, data) => {
// if this is a new type, we must initialize it as an empty array and push the first record.
if(!obj[data.type]) {
obj[data.type] = [];
obj[data.type].push({name: data.city, count: 1});
return obj;
}
// else ... check if the current city is present in that type
const existingRecord = obj[data.type].find(d => d.name === data.city);
if(!existingRecord) {
// if the city is not present in that type, we initialize it with count 1
obj[data.type].push({name: data.city, count: 1});
return obj;
}
// if the city is present, we just update count = count + 1;
existingRecord.count++;
return obj;
}, { })
现在,您可能希望将某些逻辑提取到单独的函数中以提高可读性。我不认为你需要lodash,但是如果你已经把它包含在你的项目中,那么随时可以使用它:P
答案 1 :(得分:0)
使用Lodash
var json = [{
"city": "California",
"name": "Joe",
"age": 17,
"type": "custom"
}, {
"city": "California",
"name": "Bob",
"age": 17,
"type": "predefined"
}, {
"city": "California",
"name": "Bob",
"age": 35,
"type": "custom"
}, {
"city": "Texas",
"name": "Bob",
"age": 35,
"type": "custom"
}, {
"city": "Florida",
"name": "Bob",
"age": 35,
"type": "predefined"
}];
// Solution to the problem
var updatedJson = _(json).groupBy("type").value(); // #1
_.forOwn(updatedJson, function(value, key) {
let countByCity = _(value).countBy('city').value(); // #2
let res = [];
_.forOwn(countByCity, function(value, key) {
res.push({ // #3
name: key,
count: value
});
});
updatedJson[key] = res;
});
console.log(updatedJson);
&#13;
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js"></script>
&#13;
解释
答案 2 :(得分:0)
您可以使用reduce
&amp; findIndex
var json = [{
"city": "California",
"name": "Joe",
"age": 17,
"type": "custom"
}, {
"city": "California",
"name": "Bob",
"age": 17,
"type": "predefined"
}, {
"city": "California",
"name": "Bob",
"age": 35,
"type": "custom"
}, {
"city": "Texas",
"name": "Bob",
"age": 35,
"type": "custom"
}, {
"city": "Florida",
"name": "Bob",
"age": 35,
"type": "predefined"
}];
var updatedjson = json.reduce(function(result, item) {
// check if type is present in the object
// if not present then add a key by name custom/predefined
if (!result[item.type]) {
result[item.type] = [];
// add city name and intial count
result[item.type].push({
name: item.city,
count: 1
})
} else {
// now find the index of the object whe name matches with current city
let m = result[item.type].findIndex(function(obj) {
return obj.name === item.city
})
// if no matches then add the new object to either custom/predefined
if (m === -1) {
result[item.type].push({
name: item.city,
count: 1
})
} else {
// if matches then increase the value of count
result[item.type][m].count += 1
}
}
return result;
}, {});
console.log(updatedjson)