该 $log10 运算符计算以 10 为底的数字的对数并返回结果。
语法
{
$log10: <number>
}
参数
| 参数 | DESCRIPTION |
|---|---|
<number> |
解析为正数的任何有效表达式。 |
例子
请考虑存储集合中的此示例文档。
{
"_id": "0fcc0bf0-ed18-4ab8-b558-9848e18058f4",
"name": "First Up Consultants | Beverage Shop - Satterfieldmouth",
"location": {
"lat": -89.2384,
"lon": -46.4012
},
"staff": {
"totalStaff": {
"fullTime": 8,
"partTime": 20
}
},
"sales": {
"totalSales": 75670,
"salesByCategory": [
{
"categoryName": "Wine Accessories",
"totalSales": 34440
},
{
"categoryName": "Bitters",
"totalSales": 39496
},
{
"categoryName": "Rum",
"totalSales": 1734
}
]
},
"promotionEvents": [
{
"eventName": "Unbeatable Bargain Bash",
"promotionalDates": {
"startDate": {
"Year": 2024,
"Month": 6,
"Day": 23
},
"endDate": {
"Year": 2024,
"Month": 7,
"Day": 2
}
},
"discounts": [
{
"categoryName": "Whiskey",
"discountPercentage": 7
},
{
"categoryName": "Bitters",
"discountPercentage": 15
},
{
"categoryName": "Brandy",
"discountPercentage": 8
},
{
"categoryName": "Sports Drinks",
"discountPercentage": 22
},
{
"categoryName": "Vodka",
"discountPercentage": 19
}
]
},
{
"eventName": "Steal of a Deal Days",
"promotionalDates": {
"startDate": {
"Year": 2024,
"Month": 9,
"Day": 21
},
"endDate": {
"Year": 2024,
"Month": 9,
"Day": 29
}
},
"discounts": [
{
"categoryName": "Organic Wine",
"discountPercentage": 19
},
{
"categoryName": "White Wine",
"discountPercentage": 20
},
{
"categoryName": "Sparkling Wine",
"discountPercentage": 19
},
{
"categoryName": "Whiskey",
"discountPercentage": 17
},
{
"categoryName": "Vodka",
"discountPercentage": 23
}
]
}
]
}
示例 1 - 分析销售分布
若要将每个类别的销售量分桶到商店中，请在 totalSales 字段中使用 $log 10 运算符运行查询。 然后，根据结果将类别桶化为“低”、“中”和“高”。
db.stores.aggregate([{
$match: {
_id: "40d6f4d7-50cd-4929-9a07-0a7a133c2e74"
}
},
{
$project: {
name: 1,
salesAnalysis: {
$map: {
input: "$sales.salesByCategory",
as: "category",
in: {
categoryName: "$$category.categoryName",
originalSales: "$$category.totalSales",
logScale: {
$log10: "$$category.totalSales"
},
magnitudeClass: {
$switch: {
branches: [{
case: {
$lt: [{
$log10: "$$category.totalSales"
}, 3]
},
then: "Low"
},
{
case: {
$lt: [{
$log10: "$$category.totalSales"
}, 4]
},
then: "Medium"
},
{
case: {
$lt: [{
$log10: "$$category.totalSales"
}, 5]
},
then: "High"
}
],
default: "Very High"
}
}
}
}
}
}
}
])
此查询返回以下结果：
[
{
"_id": "40d6f4d7-50cd-4929-9a07-0a7a133c2e74",
"name": "Proseware, Inc. | Home Entertainment Hub - East Linwoodbury",
"salesAnalysis": [
{
"categoryName": "Sound Bars",
"originalSales": 2120,
"logScale": 3.326,
"magnitudeClass": "Medium"
},
{
"categoryName": "Home Theater Projectors",
"originalSales": 45004,
"logScale": 4.653,
"magnitudeClass": "High"
},
{
"categoryName": "Game Controllers",
"originalSales": 43522,
"logScale": 4.639,
"magnitudeClass": "High"
},
{
"categoryName": "Remote Controls",
"originalSales": 28946,
"logScale": 4.462,
"magnitudeClass": "High"
},
{
"categoryName": "VR Games",
"originalSales": 32272,
"logScale": 4.509,
"magnitudeClass": "High"
}
]
}
]
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