apply

DataFrame的apply方法： def cal_value_percent(row,total_value): row['new_column']=row[estimated_value_col]/total_value return row df=df.apply(lambda row:cal_value_percent(row,total),axis=1) Series的apply方法： df['AJID']=df['AJID'].apply(lambda x:str(x)) 来源： https://www.cnblogs.com/aaronhoo/p/11794106.html

//实现call var that = this ; //小程序环境 function mySymbol(obj){ let unique = (Math.random() + new Date().getTime()).toString(32).slice(0,8); if(obj.hasOwnProperty(unique)){ return mySymbol(obj) }else { return unique; } } let Person = { name:'Tom', say(age = 23,city = '宁波',job = '前端'){ console.log(`我叫${this.name},今年${age},在${city},从事${job}`) } } let Person1 = { name:'Tom1' } Function.prototype.MyCall = function(context){ context =context || that; //小程序环境 PC环境为context =context || window; let fn = mySymbol(context); context.fn = this; let arg = [...arguments].slice(1); context.fn(...arg); delete

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 want to apply a LUT-filter on a video,so i decide to use FFMPEG,but i don't know how to apply this LUT image on the video , This is the LUT image: Can anyone tell me how to do this With FFMPEG ? Thanks. 回答1: You can use haldclut filter. ffplay input -vf "movie=uUyIr.png, [in] haldclut" 文章来源: How to apply a LUT filter with FFmpeg

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 am writing a class which extends Scala's immutable map with some custom constructor logic. As a simple example, say I want a map of integers to strings that is initialized as 1 -> "one", 2 -> "two" . In the REPL I can write the following. scala> import collection.immutable.HashMap import collection.immutable.HashMap scala> HashMap[Int, String](1->"one", 2->"two") res0: scala.collection.immutable.HashMap[Int,String] = Map(1 -> one, 2 -> two) In my program I'd like to use the same constructor call, but I get a "too many arguments for

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 have a file of 150M lines which updates only one table of postgresql database with such commands: UPDATE "events" SET "value_1" = XX, "value_2" = XX, "value_3" = XX, "value_4" = XX WHERE "events"."id" = SOME_ID; All id's are unique, there's no way to apply that update to several events. Currently such update takes approx few days if we run this with \i update.sql in psql. Is there any faster way to run it? 回答1: Simplest: add set synchronous_commit=off before \i update.sql Better: Split the file to parts of like 100000 updates: split -l

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: Using the PrimeFaces Demo filtering DataTable ( https://www.primefaces.org/showcase/ui/data/datatable/filter.xhtml ) as an example, I would like to be able to provide "filtering" links outside of the table for the user to click (say Volvo, Forw, BMW, etc). When the user clicks the link, I would like to switch the selected item in the manufacturer filter dropdown and apply the filter. I haven't been able to figure out how to get to the filter properties to make the change. Can this be done via javescript? How do I access the selection list

Most pro R users have advised me never to use loops in R. Use apply functions instead. The problem is that it is not that intuitive to write an apply equivalent for every for/while loop if you're not familiar with functional programming. Take the below example for instance. F <- data.frame(name = c("a", "b", "c", "d"), var1 = c(1,0,0,1), var2 = c(0,0,1,1), var3 = c(1,1,1,1), clus = c("one", "two", "three", "four")) F$ObjTrim <- "" for (i in 1:nrow(F)) { for (j in 2:(ncol(F)-1)) { if(F[i, j] == 1) {F$ObjTrim[i] <- paste(F$ObjTrim[i], colnames(F)[j], sep = " ") } } print(i) } The objective here

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: This question already has an answer here: LINQ equivalent of foreach for IEnumerable 21 answers I have recently started off with LINQ and its amazing. I was wondering if LINQ would allow me to apply a function - any function - to all the elements of a collection, without using foreach. Something like python lambda functions. For example if I have a int list, Can I add a constant to every element using LINQ If i have a DB table, can i set a field for all records using LINQ. I am using C# 回答1: A common way to approach this is to add

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 function find_country_from_connection_ip which takes an ip, and after some processing returns a country. Like below: def find_country_from_connection_ip(ip): # Do some processing return county I am using the function inside apply method. like below: df['Country'] = df.apply(lambda x: find_country_from_ip(x['IP']), axis=1) As it is pretty straightforward, what I want is to evaluate a new column from an existing column in the DataFrame which has >400000 rows. It runs, but terribly slow and throws an exception like below: ...........: