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可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: We are using itextsharp to create a single PDF from multiple PDF files. How do I insert a new page into a PDF file that has multiple pages already in the file? When I use add page it is overwriting the existing pages and only saves the 1 page that was selected. Here is the code that I am using to add the page to the existing PDF: PdfReader reader = new PdfReader(sourcePdfPath); Document document = new Document(reader.GetPageSizeWithRotation(1)); PdfCopy pdfCopy = new PdfCopy(document, new System.IO.FileStream(outputPdfPath, System.IO

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I'm using the RecyclerView like below: and my list item: see in detail this part android:background="@drawable/selector_medium_high" it's a normal selector: but when I run this code, i have no changes in background color when I touch the row.... 回答1: Set clickable , focusable , focusableInTouchMode to true in all elements of RecyclerView "list". 回答2: Add : android:background="?android:attr/selectableItemBackground" in item.xml 回答3: Adding android:background="?android:attr/selectableItemBackground" to my_list_item.xml 's root layout seems to

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I have a ListView and i am using a custom adapter to show data. Now i want to change searched text letter colour as in above screen shot. Here is the code for SearchView @Override public boolean onCreateOptionsMenu(Menu menu) { MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.actionbar_menu_item, menu); SearchManager searchManager = (SearchManager) getSystemService(Context.SEARCH_SERVICE); final SearchView searchView = (SearchView) menu.findItem(R.id.action_search) .getActionView(); searchView.setSearchableInfo

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: The following code is just to produce an example of the problem: public static void main ( String [] args ) { Collection < Integer > src = new ArrayList < Integer >(); Collection < Integer > dest = new ArrayList < Integer >(); src . add ( 2 ); src . add ( 7 ); src . add ( 3 ); src . add ( 2201 ); src . add (- 21 ); dest . add ( 10 ); while ( src . size () != 0 ) { for ( int i : dest ) { int min = Collections . min ( src ); dest . add ( min ); src . remove ( min ); } } } What I want to do is move everything from src to dest in a

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: In the examples below, resp.results is an iterator. Version1 : items = [] for result in resp.results: item = process(result) items.append(item) return iter(items) Version 2: for result in resp.results: yield process(result) Is returning iter(items) in Version 1 any better/worse in terms of performance/memory savings than simply returning items? In the "Python Cookbook," Alex says the explicit iter() is "more flexible but less often used," but what are the pros/cons of returning iter(items) vs yield as in Version 2? Also, what are the best

原始数据 const data = [{ id: 1, spec: '规格1', rules: [{ rank: 10, breaks: 100 }, { rank: 50, breaks: 10 }, { rank: 100, breaks: 5 } ] }, { id: 2, spec: '规格2', rules: [{ rank: 10, breaks: 200 }, { rank: 50, breaks: 20 }, { rank: 100, breaks: 25 } ] } ]; 使用 forEach 遍历 function skuFormat(data) { let RankList = []; data.forEach(item => { item.rules.forEach(ite => { if (RankList.indexOf(ite.rank) === -1) RankList.push(ite.rank); }) }) let newData = []; RankList.forEach(item => { newData.push({ rank: item, skus:[] }) }) newData.forEach(item=>{ data.forEach(ite=>{ let Remark={ id:ite.id, spec:ite.spec,

本文讲梯度下降（Gradient Descent）前先看看利用梯度下降法进行监督学习（例如分类、回归等）的一般步骤： 1， 定义损失函数（Loss Function） 2， 信息流forward propagation，直到输出端 3， 误差信号back propagation。采用“链式法则”，求损失函数关于参数Θ的梯度 4， 利用最优化方法（比如梯度下降法），进行参数更新 5， 重复步骤2、3、4，直到收敛为止 所谓损失函数，就是一个描述实际输出值和期望输出值之间落差的函数。有多种损失函数的定义方法，常见的有均方误差（error of mean square）、最大似然误差（maximum likelihood estimate）、最大后验概率（maximum posterior probability）、交叉熵损失函数（cross entropy loss）。本文就以均方误差作为损失函数讲讲梯度下降的算法原理以及用其解决线性回归问题。在监督学习下，对于一个样本，它的特征记为x（如果是多个特征，x表示特征向量），期望输出记为t（t为target的缩写），实际输出记为o（o为output的缩写）。两者之间的误差e可用下式表达（为了节省时间，各种算式就用手写的了）： 前面的系数1/2主要是为了在求导时消掉差值的平方项2。如果在训练集中有n个样本，可用E来表示所有样本的误差总和

The day of opening of the greatest shop in the world is coming. To show the full potential of their shop, in particular, the unbelievable speed of the cash desks, the owners of the shop came up with the following move: n most average customers will be let into the shop, and the cash desks will be opened only after all customers will choose their purchases and take their places in the queues. The problem is that if the customers walk along the cash desks and choose the optimal queue, the process can last for several hours. That's why you are asked to choose queues for all customers

<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> <script src="./lib/vue-2.4.0.js"></script> </head> <body> <div id="app"> <div> <label>Id: <input type="text" v-model="id"> </label> <label>Name: <input type="text" v-model="name"> </label> <input type="button" value="添加" @click="add"> </div> <!-- 注意： v-for 循环的时候，key 属性只能使用 number获取string --> <!-- 注意： key 在使用的时候，必须使用 v-bind 属性绑定的形式，指定 key 的值 --> <!-- 在组件中，使用v-for循环的时候，或者在一些特殊情况中，如果 v

　　微信小程序中wx:for遍历默认元素为item，但是如果我们设计多层遍历的时候我们就需要自定义item的字段名以及key的键名 wx:for="{{item.goodsList}}" wx:for-item="ite" wx:for-key="idx" wx:key="{{idx}}" 　　这样子元素就被设置成ite了，而key则为idx 来源： https://www.cnblogs.com/gitByLegend/p/11389829.html