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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: Computer[] labComputers = new Computer[10]; with public class Computer { ... void toString(){ // print computer specs } } public class Notebook extends Computer{ ... void toString(){ // print computer specs + laptop color } } each subscripted variable labComputers[i] can reference either a Computer object or a Notebook object because Notebook is a subclass of Computer . For the method call labComputers[i].toString() , polymorphism ensures that the correct toString method is called. I wonder what if we do Notebook[] labComputers = new

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 searched on the web for over two days now, and probably have looked through most of the online documented scenarios and workarounds, but nothing worked for me so far. I am on AWS SDK for PHP V2.8.7 running on PHP 5.3. I am trying to connect to my S3 bucket with the following code: // Create a `Aws` object using a configuration file $aws = Aws::factory('config.php'); // Get the client from the service locator by namespace $s3Client = $aws->get('s3'); $bucket = "xxx"; $keyname = "xxx"; try { $result = $s3Client->putObject(array( 'Bucket

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: ready: function() { this.$watch('things', function(){console.log('a thing changed')}, true); } things is an array of objects [{foo:1}, {foo:2}] $watch detects when an object is added or removed, but not when values on an object are changed. How can I do that? 回答1: You should pass an object instead of boolean as options , so: ready: function () { this.$watch('things', function () { console.log('a thing changed') }, {deep:true}) } Or you could set the watcher into the vue instance like this: new Vue({ ... watch: { things: { handler: function

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 experienced a RuntimeWarning RuntimeWarning: invalid value encountered in less_equal Generated by this line of code of mine: center_dists[j] <= center_dists[i] Both center_dists[j] and center_dists[i] are numpy arrays What might be the cause of this warning ? 回答1: That's most likely happening because of a np.nan somewhere in the inputs involved. An example of it is shown below - In [1]: A = np.array([4, 2, 1]) In [2]: B = np.array([2, 2, np.nan]) In [3]: A<=B RuntimeWarning: invalid value encountered in less_equal Out[3]: array([False,

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: As of Swift 2.0 it seems we can get closer to extensions of generic types applicable to predicated situations. Although we still can't do this: protocol Idable { var id : String { get } } extension Array where T : Idable { ... } ...we can now do this: extension Array { func filterWithId<T where T : Idable>(id : String) -> [T] { ... } } ...and Swift grammatically accepts it. However, for the life of me I cannot figure out how to make the compiler happy when I fill in the contents of the example function. Suppose I were to be as explicit as

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 follow this links How to append many numpy files into one numpy file in python to put all my numpy files in one file. Now, I need to plot my file which contains many arrays, each array contain some float number: this is my final code to append arrays in one big array: import matplotlib.pyplot as plt import numpy as np import glob import os, sys fpath ="/home/user/Desktop/OutFileTraces.npy" npyfilespath="/home/user/Desktop/test" os.chdir(npyfilespath) npfiles= glob.glob("*.npy") npfiles.sort() all_arrays = [] with open(fpath,'ab') as f

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: By default, Magento got Order information such as shipping, address, but not much about product. I want to get the latest order information included product url, product thumbnail, etc. I try to join the order flat tables to get information. But I found there's only product name in the sales_flat_order_item table. So how can i get the product url and thumbnail? I wrote a function in block to get some information about an order, newbie to magento, would you like to tell me if this is a good method to get data from magento, if not, so

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: In a Cocoa Touch project, I need a specific class to have not only a single delegate object, but many of them. It looks like I should create an NSArray for these delegates; the problem is that NSArray would have all these delegates retained, which it shouldn't (by convention objects should not retain their delegates). Should I write my own array class to prevent retaining or are there simpler methods? Thank you! 回答1: I found this bit of code awhile ago (can't remember who to attribute it to). It's quite ingenius, using a Category

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 need to remove the duplicate items from an array without harming their order. Please Consider this array of data var array = [ { person: { amount: [1,1] } }, { person: { amount: [1,1] } }, { person: { amount: [2,1] } }, { person: { amount: [1,2] } }, { person: { amount: [1,2] } }]; I understand that it can be done by using new Set([iterable]) but can't work with this array. If anyone have an idea, please help. Thanks in advance. 回答1: You could convert the elements to JSON and use those as keys for a Map, and then convert that back to an

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 pretty simple $lookup aggregation query like the following: {'$lookup': {'from': 'edge', 'localField': 'gid', 'foreignField': 'to', 'as': 'from'}} When I run this on a match with enough documents I get the following error: Command failed with error 4568: 'Total size of documents in edge matching { $match: { $and: [ { from: { $eq: "geneDatabase:hugo" } }, {} ] } } exceeds maximum document size' on server All attempts to limit the number of documents fail. allowDiskUse: true does nothing. Sending a cursor in does nothing. Adding in a