population

Is it possible to populate objects in map schema type?

由 ↘锁芯ラ 提交于 2021-01-01 00:02:59
问题 I have schema type Map in my mongoose model. In this map, each element has reference to another model. I know that it's possible to populate attributes in array, but how about Map type? Be cause nesting like "map_type_attribute.some_attribute_to_populate" doesn't work. :) This is my model: const Mongoose = require('mongoose'); const parameter = Mongoose.Schema({ definition: { type: Mongoose.Schema.Types.ObjectId, ref: 'Definition', }, value: {}, }, {_id: false}); const schema = Mongoose

Mongoose 使用之 Population

由 跟風遠走 提交于 2020-04-06 22:34:05
何为 Population 用过 MongoDB 的人应该都知道它是没有关系型数据库里的 join 特性的，这意味着当我们使用 MongoDB 读取某个 document 及其关联的 document 的字段的时候，变得尤为麻烦。 基于此，Mongoose 封装了一个 population 的功能，当你在定义 Schema 的时候指定了某个 field 是引用了另一个 Schema ，那么你在获取 document 的时候就可以使用 populate 方法让 Mongoose 帮你通过引用 Schema 和 id 找到关联的另一个 document，并且用该 document 的内容替换掉原来引用字段的内容，使引用的 ducoment 使用起来就像是内嵌的 document 一样方便。 定义带有引用字段的 Schema 首先，如果要使用这个功能，必须给你的“外键字段”定义 Mongoose 的“外键约束”（这里借用关系型数据库的术语，只是为了帮助理解）。假设我们有一个用户的 Schema ，其中有一个字段是followings，保存用户关注了的其他用户，类似微博。Mongoose 的 Schema 定义如下： var mongoose = require('mongoose') , Schema = mongoose.Schema var UserSchema = Schema({

Sampling a specific age distribution from a dataset

由 ≡放荡痞女 提交于 2019-12-23 02:32:54
问题 Suppose I have a dataset with 1,000,000 observations. Variables are age, race, gender. This dataset represents the whole US. How can I draw a sample of 1,000 people from this dataset, given a certain age distribution? E.g. I want this datset with 1000 people distributed like this: 0.3 * Age 0 - 30 0.3 * Age 31 - 50 0.2 * Age 51 - 69 0.2 * Age 70 - 100 Is there a quick way to do it? I already created a sample of 1000 people with the desired age distribution, but how do I combine that now with

Dynamically populate a field based on dropdown selection (Javascript / HTML)

由 断了今生、忘了曾经 提交于 2019-12-21 16:49:45
问题 I am looking for some help in coding my companies website. We are trying to create a custom "part number generator" based on selections made from a dropdown box. Our goal is that when a user picks an option in the dropdown box that it dynamically fills in a box underneath, eventually creating a part number. The attached screenshot is a good visual representation of the design and where we want the output boxes. We are looking to do it in JavaScript and HTML. The code we are using currently to

Hamming weight/population count in T-SQL

由 我的梦境 提交于 2019-12-17 20:56:35
问题 I'm looking for a fast way to calculate the hamming weight/population count/"the number of 1 bits" of a BINARY(1024) field. MySQL has a BIT_COUNT function that does something like that. I couldn't find a similar function in T-SQL? Or would you suggest storing the binary data in a field of another type? If you don't know what I'm talking about, here's a Wikipedia article about the hamming weight. 回答1: You could use a helper table with precalculated Hamming weights for small numbers, like bytes

YUI 2.5. Populating a dropdown from XML

由 你离开我真会死。 提交于 2019-12-13 05:07:20
问题 Currently editing an application built using YUI 2.5 and Perl. I need to populate a dropdown from an xml file, and only specific rows are to be used depending on the attributes of the node. Unfortunately, there isn't the DropdownCellEditor widget in YUI 2.5 (as far as I'm aware, this didn't come in until 2.6(?)). Does anyone have any ideas? I'm thinking I should probably just update YUI as there seems to be a lot of useful functionality missing in this very old version. The code the original

SSE 4 popcount for 16 8-bit values?

由 时光总嘲笑我的痴心妄想 提交于 2019-12-09 18:00:42
问题 I have the following code which compiles with GCC using the flag -msse4 but the problem is that the pop count only gets the last four 8-bits of the converted __m128i type. Basically what I want is to count all 16 numbers inside the __m128i type but I'm not sure what intrinsic function call to make after creating the variable popA . Somehow popA has to be converted into an integer that contains all the 128-bits of information? I suppose theres _mm_cvtsi128_si64 and using a few shuffle few

Creating data in Prefuse

由 你说的曾经没有我的故事 提交于 2019-12-09 06:40:16
问题 I am new to Prefuse. The demo examples are all loaded data from a file/database. Is there any way to create the data dynamically instead of loading from file. For example, I want to create a tree data structure and visualize this. Any simple working example would be really helpful for me. 回答1: I've just been attacking this problem. Here's a tweaked version of Example.java which shows one way to make it happen. Instead of loading data from socialnet.xml , I'm generating it programatically

Choosing individuals from a population, by a fitness function

由 徘徊边缘 提交于 2019-12-07 02:26:52
问题 I've been working on an algorithm, where I need to choose n individuals from a population of size k, where k is much bigger than n. All individuals have a fitness value, therefore the selection should favor higher fitness values. However, I don't want to simply choose best n individuals, the worse ones should have a chance also. (Natural selection) So, I decided to find the min and max fitness values within population. So, any individual would have p = (current - min) / (max - min)

Sampling a specific age distribution from a dataset

由 此生再无相见时 提交于 2019-12-07 02:10:27
Suppose I have a dataset with 1,000,000 observations. Variables are age, race, gender. This dataset represents the whole US. How can I draw a sample of 1,000 people from this dataset, given a certain age distribution? E.g. I want this datset with 1000 people distributed like this: 0.3 * Age 0 - 30 0.3 * Age 31 - 50 0.2 * Age 51 - 69 0.2 * Age 70 - 100 Is there a quick way to do it? I already created a sample of 1000 people with the desired age distribution, but how do I combine that now with my original dataset? As an example, this is how I have created the population distribution of Maine:
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