lag

问题 I am trying to make multiple lags using the least amount of code possible in dplyr, while sticking to tidy eval. The following Standard Evaluation (SE) code works: #if(!require(dplyr)) install.packages("dplyr"); library(dplyr) a=as_tibble(c(1:100)) lags=3 lag_prefix=paste0("L", 1:lags, ".y") multi_lag=setNames(paste("lag(.,", 1:lags, ")"), lag_prefix) a %>% mutate_at(vars(value), funs_(multi_lag)) #final line # A tibble: 100 x 4 value L1.y L2.y L3.y <int> <int> <int> <int> 1 1 NA NA NA 2 2 1

问题 i have an application where i am loading large amount of images from database and showing them in my gallery, what i was doing earlier is i was getting photo url (local identifier) from PHAsset and then accessing the image using PHCacheManager, but it slows down my scrolling and also shows lags while updating images in new cell. I was trying to use SDWebImage here by passing the url to the sd_setImageWithURL: method, however i found out that the URL is actually a local identifier which is not

问题 I have a simple game where you are in a rocket and you avoid planets that come down the screen. When I play a short sub second long sound my game jitters and lags whilst it plays it and then returns to normal. Does any one know why this might be? 回答1: AVAudioPlayer, while the sound plays on a different thread, will cause a long delay initializing itself on its current thread. My solution was to use AVAudioPlayer only for music, since the high level API made it useful for that, but even then

问题 I have a sample data as below and wanting to get a desired o/p, please help me with some idea. I want the o/p of prev_diff_value of the 3rd,4th row to be 2015-01-01 00:00:00 instead of 2015-01-02 00:00:00. with dat as ( select 1 as id,'20150101 02:02:50'::timestamp as dt union all select 1,'20150101 03:02:50'::timestamp union all select 1,'20150101 04:02:50'::timestamp union all select 1,'20150102 02:02:50'::timestamp union all select 1,'20150102 02:02:50'::timestamp union all select 1,

问题 I have a dataset in which I want to fill missing values witht the closest non-missing value. I found two elegant solutions in the answers to this question, but I don't understand why they are not working for me. Table: create table Tab1(data date, V1 number); insert into Tab1 values (date '2000-01-01', 1); insert into Tab1 values (date '2000-02-01', 1); insert into Tab1 values (date '2000-03-01', 1); insert into Tab1 values (date '2000-04-01', 1); insert into Tab1 values (date '2000-05-01',

问题 I’m trying to implement a simple “fixed headers” table. I know this can in theory be done with CSS only, but it doesn’t work very well when it comes to OSX Lion and its disappearing scrollbars. So I’m doing it with jQuery. An approach is simple, it’s just 1.5 lines of code: $('.inbox').scroll(function() { $(this).find('.inbox-headers').css('top', $(this).scrollTop()); }); Demo . This works fine and smooth in Firefox, but lags horribly in webkit browsers. Why is that happening and how do I

问题 So I am facing a problem A table view gets slower (responses slower to scrolling, tapping) after reloading/adding rows for a couple of times So after the user logs in, the app downloads 10 "WorldMessages" . It is loaded into this table view. If the user scrolls down, it calls a function which loads more 10: loadOlderOwnWorldMessages() Each cell has a tapGestureRecognizer + longPressGestureRecognizer And I have to mention that If the user reloads the tableView, then it clears the data and

问题 I have a data set like below, Lot Size Reported QTY Qty Balance 150 100 150 100 150 80 150 80 150 5 The Qty Balance needs to calculated as follows, Row 1 = Lot Size - Reported Qty (row1) => 150-100 = 50 Row 2 = Reported Qty (row1) - Reported Qty(row2) => 100-100 =0 Row 3 = Reported Qty (row2) - Reported Qty(row3) => 100-80 =20 ... till the last row My expected result is Lot Size Reported QTY Qty Balance 150 100 50 150 100 0 150 80 20 150 80 0 150 5 75 How do I achieve this in a query? 回答1:

问题 How to use LAG function to get the updated previous row value (without using Recursive CTE ). Please check the screenshot for sample output Query Tried Declare @Tbl as Table(SNO Int,Credit Money,Debit Money,PaidDate Date) Insert into @Tbl SELECT * FROM (VALUES (1,0,12,'7Jan16'), (2,10,0,'6Jan16'), (3,15,0,'5Jan16'), (4,0,5,'4Jan16'), (5,0,3,'3Jan16'), (6,0,2,'2Jan16'), (7,20,0,'1Jan16')) AS X(SNO,Credit,Debit,PaidDate) Select T.SNO, T.Credit, T.Debit, TotalDebit = Case When Credit < LAG(T

问题 I have a ListView in my app, and I've over-ridden the getView() method so I can change the row's ImageView src depending on the row's text. The problem is, I've noticed the ListView scrolling is lagging, and when I check DDMS, it seems the Garbage Collector is being called everytime the ListView is being scrolled, thus slowing the scrolling. I've also noticed the Garbage Collector being called in a different part of my app, when reading lines from a BufferedReader, which makes opening a 2,000