投稿時間:2023-03-18 23:13:12 RSSフィード2023-03-18 23:00 分まとめ(17件)

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python	Pythonタグが付けられた新着投稿 - Qiita	Pythonファイルの.exe化	https://qiita.com/reiji990/items/260891de37edb757e494	自分	2023-03-18 22:50:35
python	Pythonタグが付けられた新着投稿 - Qiita	リストで指定要素を先頭に持ってくる（メモです）	https://qiita.com/redsquid/items/55d9bca147fee313998d	nimporttimestimeperfcount	2023-03-18 22:38:06
python	Pythonタグが付けられた新着投稿 - Qiita	PythonのSubProcessでPythonファイルを実行する	https://qiita.com/sin471/items/497d7eb52701150cb183	subprocess	2023-03-18 22:32:15
python	Pythonタグが付けられた新着投稿 - Qiita	対応する3次元点群データから回転行列を推定する方法	https://qiita.com/Hiroaki-K4/items/8e02d76ad060e9efffaf	回転行列	2023-03-18 22:29:11
js	JavaScriptタグが付けられた新着投稿 - Qiita	ChatGPTを使ってほんの数時間でゲーム「Straight Line Challenge」をリリースしました	https://qiita.com/keitomatsuri/items/59a4622348add5ae1279	chatgpt	2023-03-18 22:38:30
Ruby	Rubyタグが付けられた新着投稿 - Qiita	rbenvでRubyをインストールしようとしてエラー	https://qiita.com/hopitaf/items/d130726399ff590ba6bf	brewinstalllibyaml	2023-03-18 22:41:46
Linux	Ubuntuタグが付けられた新着投稿 - Qiita	Windows 11 の Linux でクラウド開発する	https://qiita.com/fsdg-adachi_h/items/6119ab05d8b13527efd8	fsdgadachih	2023-03-18 22:51:56
Docker	dockerタグが付けられた新着投稿 - Qiita	Windows 11 の Linux でクラウド開発する	https://qiita.com/fsdg-adachi_h/items/6119ab05d8b13527efd8	fsdgadachih	2023-03-18 22:51:56
Docker	dockerタグが付けられた新着投稿 - Qiita	Dockerの基本	https://qiita.com/nichidai3_0514/items/91d0858dfef7a39b07bd	docker	2023-03-18 22:47:58
Azure	Azureタグが付けられた新着投稿 - Qiita	Windows 11 の Linux でクラウド開発する	https://qiita.com/fsdg-adachi_h/items/6119ab05d8b13527efd8	fsdgadachih	2023-03-18 22:51:56
Git	Gitタグが付けられた新着投稿 - Qiita	Git コマンド 業務でつかう主なもの	https://qiita.com/RikuMoto/items/b36bf60fce5e37441d8e	gitbush	2023-03-18 22:08:20
Ruby	Railsタグが付けられた新着投稿 - Qiita	テストに関わる基礎知識	https://qiita.com/Bjp8kHYYPFq8MrI/items/537325c5ffa6ca612715	箇条書き	2023-03-18 22:44:14
海外TECH	DEV Community	Python: How simple string concatenation can kill your code performance	https://dev.to/fayomihorace/python-how-simple-string-concatenation-can-kill-your-code-performance-2636	Python How simple string concatenation can kill your code performanceNote a video version of this tutorial is available Python How simple string concatenation can kill your code performance In general there is no problem with string concatenationString concatenation is one of the first and most used features in programming You learn variables basics integers booleans and strings It s even one of the first things we learn in the python official Documentation So yes string concatenation is not bad and it might even be impossible to do programming without needing to concatenate strings for one reason or another Although yes like almost any useful tool or feature when used the wrong way it can lead to really bad effects So it s important to be aware of how to use them correctly When string concatenation could be dangerous You should pay attention to string concatenation when those two conditions are met The feature is a performance critical one Example a text data analysis feature on a web application that is running and a user in the website interface is waiting to get back the result so your code should be as fast as possible You re dealing with a lot of concatenation starting from because of a loop maybe and or the strings you re concatenating are really really long That can lead to significant overhead in terms of memory allocation and garbage collection slow down your code and in the worse case just make your code crash in production And that also means it s totally safe to use string concatenation when those conditions are not met and you re sure that these conditions can never be met in the future So for instance firstname John lastname Joe fullname fistname lastnameis totally okay because there is no way someone s name can become long enough to create a performance issue Anyways not in this world Why string concatenation is dangerous in those cases In Python strings are immutable objects which means that every time a string is concatenated with another string a new string object is created in memory To illustrate that let s run this simple code my str Hello print f my str my str print f id id my str my str World print f n my str my str print f id id my str Note Python id function returns the identity of an object The identity of an object is an integer which is guaranteed to be unique and constant for this object during its lifetime The output will be my str Helloid my str Hello Worldid As you can see the id of the string before the concatenation and after are not the same so python has created a new string The solution to that issue and a comparison with string concatenationTo address this performance issue you can use alternative techniques such as using a list to hold the individual string components and then joining them together using the join method Python doesn t create a new list each time you append an element and the join method is optimized to avoid creating a new string object for each string in the list it has to join import timeit Concatenate stringsstart time timeit default timer s for i in range s a elapsed time concat timeit default timer start timeprint Time taken for string concatenation elapsed time concat Join stringsstart time timeit default timer lst for i in range lst append a s join lst elapsed time join timeit default timer start timeprint Time taken for string join elapsed time join join performance elapsed time concat elapsed time join elapsed time concatprint Performance gained with join join performance In this example we generate a string of length by concatenating the string a times using both the string concatenation and the join method The output shows that the join method is significantly faster than the concatenation method Time taken for string concatenation Time taken for string join Performance gained with join As you can see by using join we have increased the time performance by almost which is wonderful Diving deep into the why Math and a Big O explanationThis behavior could also be explained using BigO notation especially the time complexity Let s focus on the concatenation part of our previous code We have a string s that we concatenate M times with a string c of length on length N s c c for i in range s cSo here N and M Keep this in mind The complexity to create a string of length N is O N So because concatenation creates a new stringof length len s c the complexity of the concatenation at each iteration is the length of s at the previous iteration length of string c As you can see the total or overall complexity is … M which we can mathematically approximate at M M And by neglecting the minority exponents we have Let s try to so see the time complexity with the join approach lst c c for i in range lst append c s join lst In this case we have two steps The loop to create the listfor i in range lst append c The complexity here is O M and in our case M because python has to execute lst append c M times The join s join lst Here the complexity is O T where T total length of the final string after the join and in our case T N M So the final time complexity is NM M M N and we can approximate it as O MN Which is far better than O M for the simple concatenation That is for this tutorial I hope you understand when and why string concatenation could be dangerous so you can use join instead when it s needed Thanks for reading don t forget to checkout the video version on our youtube channel here and I see you at the next one Take care	2023-03-18 13:25:26
海外TECH	DEV Community	Top 20 Tools used by IT Professionals	https://dev.to/yashsu/top-20-tools-used-by-it-professionals-1fil	Top Tools used by IT Professionals	2023-03-18 13:12:10
ニュース	BBC News - Home	SNP chief executive Peter Murrell resigns over membership row	https://www.bbc.co.uk/news/uk-scotland-65000606?at_medium=RSS&at_campaign=KARANGA	effect	2023-03-18 13:50:07
ニュース	BBC News - Home	Pakistan: Imran Khan supporters clash with police outside court	https://www.bbc.co.uk/news/world-asia-64998922?at_medium=RSS&at_campaign=KARANGA	gifts	2023-03-18 13:22:55
ニュース	BBC News - Home	Duhan van der Merwe scores incredible first try for Scotland against Italy in Six Nations	https://www.bbc.co.uk/sport/av/rugby-union/65000943?at_medium=RSS&at_campaign=KARANGA	Duhan van der Merwe scores incredible first try for Scotland against Italy in Six NationsWatch as Duhan van der Merwe scores a sensational opening try for Scotland as they host Italy in the Six Nations	2023-03-18 13:10:27