我有一个对象数组。每个gateType:entry都需要跟gateType:exit个对象。
问题是某些条目对象和一些退出对象丢失/跳过。我需要创建一个包含缺少对象的对象数组。
[{
"dateTime": "2016-01-28 15:18:26",
"gateType": "entry",
}, {
"dateTime": "2016-01-28 15:18:27",
"gateType": "exit",
}, {
"dateTime": "2016-01-28 15:19:26",
"gateType": "entry",
}, {
"dateTime": "2016-01-28 15:19:27",
"gateType": "exit",
}, {
"dateTime": "2016-01-28 15:20:26",
"gateType": "entry",
},
// here is the exit object is missing for above
{
"dateTime": "2016-01-28 15:21:25",
"gateType": "entry",
}, {
"dateTime": "2016-01-28 15:21:26",
"gateType": "exit",
}, {
"dateTime": "2016-01-28 15:22:25",
"gateType": "entry",
}, {
"dateTime": "2016-01-28 15:22:26",
"gateType": "exit",
},
// here is the entry object is missing for below
{
"dateTime": "2016-01-28 15:23:26",
"gateType": "exit",
}]
每个entry都需要跟exit。但是你可以看到一些入口或出口对象不存在。
以上示例的解决方案是：
[{
"dateTime": "2016-01-28 15:20:26",
"gateType": "exit",
},{
"dateTime": "2016-01-28 15:23:26",
"gateType": "enty",
}]
我的解决方案是这样的，但它并没有像我期望的那样工作：
function detectMissingOnes(rows) {
var missings = [];
var current = null;
rows.forEach(function (key, index) {
if (index == 0) {
if(key.gateType == "exit"){
var resultDate = moment(key.dateTime);
resultDate = resultDate.subtract(1, 'seconds').format("YYYY-MM-DD HH:mm:ss");
missings.push({
dateTime: resultDate,
gateNumber: key.gateNumber,
gateType: "entry",
personId: key.personId,
fix: 1
});
}
current = key;
return true;
}
if (current.gateType == key.gateType) {
var type = key.gateType == "entry" ? "exit" : "entry";
var resultDate = moment(current.dateTime);
if(type == "entry"){
resultDate = resultDate.subtract(1, 'seconds').format("YYYY-MM-DD HH:mm:ss");
}else {
resultDate = resultDate.add(1, 'seconds').format("YYYY-MM-DD HH:mm:ss");
}
missings.push({
dateTime: resultDate,
gateNumber: current.gateNumber,
gateType: type,
personId: current.personId,
fix: 1
});
}
current = key;
});
return missings;
}
你能不能用或不用lodash来编写算法？
答案 0 :(得分：1)
试试这个：
ref.child('messages_per_user').child('user1').on('value', function(snapshot) {
snapshot.forEach(function(messageSnapshot) {
ref.child('notifications').child(messageSnapshot.key).once('value', function(notificationSnapshot) {
console.log(notificationSnapshot.val());
})
});
});
答案 1 :(得分：1)
以下是返回缺失记录的代码。在你的问题中，你没有提到在缺失的记录中添加/减去第二个，但是在你的代码中它存在，所以我做了同样的事情。
我没有使用任何库，所以即使是使用标准JavaScript函数完成秒的操作，也会使它更长一些。
此实时片段允许您输入输入数组（JSON），并获取函数的结果（也是JSON）。
// main algorithm:
function detectMissingOnes(rows) {
var collect = rows.reduce(function (collect, curr) {
var expectedMove = collect.openEntry ? "exit" : "entry";
var expectedPerson = collect.openEntry ? collect.openEntry.personId : curr.personId;
console.log('expected move: ', expectedMove, ' person: ', expectedPerson);
console.log('current move: ', curr.gateType, ' person:', curr.personId);
if (expectedMove == curr.gateType &&
expectedPerson == curr.personId) {
console.log('ok');
// OK, we have the expected gate type and personID.
// If this is an entry, keep track of it, otherwise clear tracks
collect.openEntry = collect.openEntry ? null : curr; // toggle
} else {
console.log('mismatch');
// not OK, add to orphans list
if (collect.openEntry) collect.orphans.push(collect.openEntry);
if (curr.gateType == 'exit') collect.orphans.push(curr);
// If this is an entry, replace previous track
collect.openEntry = curr.gateType == 'entry' ? curr : null;
}
return collect;
}, {orphans: [], openEntry: null}); // initial value of collect
// if last one was an "entry", add it to the orphans list
if (collect.openEntry) {
collect.orphans.push(collect.openEntry);
}
// for all orphans: return the missing counter part.
return collect.orphans.map(function(orphan) {
var mydate = new Date(orphan.dateTime.replace(/^(.{10}) (.{8})$/, '$1T$2Z'))
// add/subtract one second:
mydate = new Date(+mydate + 1000*(orphan.gateType == "entry" ? 1 : -1));
return {
id: orphan.id,
dateTime: mydate.toISOString().replace(/^(.{10})T(.{8}).*$/, '$1 $2'),
gateNumber: orphan.gateNumber,
gateType: orphan.gateType == "entry" ? "exit" : "entry",
personId: orphan.personId,
fix: orphan.fix
};
});
}
// default input data:
var data = [
{
"id": 517,
"dateTime": "2016-01-29 13:17:46",
"gateNumber": "192.168.1.206",
"gateType": "exit",
"personId": 1,
"fix": 0
},
{
"id": 568,
"dateTime": "2016-01-29 14:03:44",
"gateNumber": "192.168.1.203",
"gateType": "entry",
"personId": 1,
"fix": 0
},
{
"id": 675,
"dateTime": "2016-01-29 14:10:07",
"gateNumber": "192.168.1.203",
"gateType": "entry",
"personId": 1,
"fix": 0
},
{
"id": 108,
"dateTime": "2016-01-29 14:11:51",
"gateNumber": "192.168.1.205",
"gateType": "entry",
"personId": 1,
"fix": 0
},
{
"id": 170,
"dateTime": "2016-01-28 14:27:58",
"gateNumber": "192.168.1.206",
"gateType": "exit",
"personId": 2,
"fix": 0
},
{
"id": 66,
"dateTime": "2016-01-28 14:33:07",
"gateNumber": "192.168.1.200",
"gateType": "exit",
"personId": 2,
"fix": 0
},
{
"id": 395,
"dateTime": "2016-01-28 16:26:04",
"gateNumber": "192.168.1.206",
"gateType": "exit",
"personId": 2,
"fix": 0
}
];
// Get input controls:
var input = document.getElementById('input');
var output = document.getElementById('output');
var button = document.getElementById('button');
// default input value:
input.value = JSON.stringify(data, null, 2);
// execute process on button click:
button.onclick = function () {
var data = JSON.parse(input.value);
var missing = detectMissingOnes(data);
output.textContent = JSON.stringify(missing, null, 2);
}div { bottom: 0; right: 0; left: 0; top: 0; position: absolute }
table { with: 100%; height: 100% }
tr.page { with: 100%; height: 100% }
td { vertical-align: top; width: 50%}
textarea { min-width: 320px; width: 100%; height:100% }<div class="big"><table border=1>
<tr><th>Enter input (JSON):<button id="button">Process</button></th>
<th>Output</th></tr>
<tr class="page"><td><textarea id="input"></textarea></td>
<td><pre id="output"></pre></td></tr>
</table></div>
该函数不会改变传递的参数（数组）。返回的数组仅列出缺少的对象。请注意，如果对象中有其他属性，则需要调整代码。