subset

I'm a bit confused between subarray, subsequence & subset if I have {1,2,3,4} then subsequence can be {1,2,4} OR {2,4} etc. So basically I can omit some elements but keep the order. subarray would be( say subarray of size 3) {1,2,3} {2,3,4} Then what would be the subset? I'm bit confused between these 3. Wilson In my opinion, if the given pattern is array, the so called subarray means contiguous subsequence . For example, if given {1, 2, 3, 4}, subarray can be {1, 2, 3} {2, 3, 4} etc. While the given pattern is a sequence, subsequence contain elements whose subscripts are increasing in the

I have a list in R some 10,000 elements long. Say I want to select only elements, 5, 7, and 9. I'm not sure how I would do that without a for loop. I want to do something like mylist[[c(5,7,9]] but that doesn't work. I've also tried the lapply function but haven't been able to get that working either. mylist[c(5,7,9)] should do it. You want the sublists returned as sublists of the result list; you don't use [[]] (or rather, the function is [[ ) for that -- as Dason mentions in comments, [[ grabs the element. 来源： https://stackoverflow.com/questions/12119019/select-multiple-elements-from-a-list

This is very similar to a question applying a common function to multiple columns of a data.table uning .SDcols answered thoroughly here . The difference is that I would like to simultaneously apply a different function on another column which is not part of the .SD subset. I post a simple example below to show my attempt to solve the problem: dt = data.table(grp = sample(letters[1:3],100, replace = TRUE), v1 = rnorm(100), v2 = rnorm(100), v3 = rnorm(100)) sd.cols = c("v2", "v3") dt.out = dt[, list(v1 = sum(v1), lapply(.SD,mean)), by = grp, .SDcols = sd.cols] Yields the following error: Error

I want to create different methods for a class called Multiset . I have all the required methods, but I'm unsure of how to write intersection, union, and subset methods. For intersection and union, my code starts like this: def intersect(var) x = Multiset.new end Here is an example: X = [1, 1, 2, 4] Y = [1, 2, 2, 2] then the intersection of X and Y is [1, 2] . Mike Lewis Utilizing the fact that you can do set operations on arrays by doing & (intersection), - (difference), and | (union). Obviously I didn't implement the MultiSet to spec, but this should get you started: class MultiSet attr

软件版本：VIVADO2017.4 操作系统：WIN10 64bit 硬件平台：适用米联客 ZYNQ系列开发板 米联客(MSXBO)论坛： www.osrc.cn 答疑解惑专栏开通，欢迎大家给我提问！！ 8.1概述 本章向大家介绍了FFT的原理，然后使用官方给出的代码使用HLS生成了两个FFT的IP，之后在VIVADO中将其封装成了一个可供之后章节使用的IP。本章需要重点掌握的是FFT的原理和熟练的掌握HLS的开发流程。本章参考了以下文献： http://www.xuebuyuan.com/539160.html http://blog.csdn.net/sshcx/article/details/1651616 8.2 FFT原理介绍 FFT是离散傅立叶变换的快速算法，可以将一个信号变换到频域。有些信号在时域上是很难看出什么特征的，但是如果变换到频域之后，就很容易看出特征了。这就是很多信号分析采用FFT变换的原因。另外，FFT可以将一个信号的频谱提取出来，这在频谱分析方面也是经常用的。在笔者参与的几个项目中就有几个使用到了FFT，因此在这里准备在HLS上实现这一算法。另外在后面的几个实验中我们都用到了这一算法，因此前面先对它进行讲解，方便大家在接下来的实验中进行使用。 FFT结果的物理意义网上有一大神圈圈对此做了详细的描述，我们在这里摘录如下方便大家理解FFT。 一个模拟信号

I have a question. I want to make a barplot with the mean and errorbars, where it is grouped for two factors. To get the mean and the standard errors I used the function tapply. However for one of the factor I want to drop one level. So what I did was did: dataFE <- data[-which(plant=="FS"),] # this works fine, I get exactly the data set I want without the FS level of the factor plant Then to get the mean and standard error I use this: means <- with(dataFE, as.matrix(tapply(leaves, list(plant, Orchestia), mean), nrow=2) e <- with(dataFE, as.matrix(tapply (leaves, list(plant, Orchestia),

This might an easy one. Here's the data: dat <- read.table(header=TRUE, text=" Seg ID Distance Seg46 V21 160.37672 Seg72 V85 191.24400 Seg373 V85 167.38930 Seg159 V147 14.74852 Seg233 V171 193.01636 Seg234 V171 200.21458 ") dat Seg ID Distance Seg46 V21 160.37672 Seg72 V85 191.24400 Seg373 V85 167.38930 Seg159 V147 14.74852 Seg233 V171 193.01636 Seg234 V171 200.21458 I am intending to get a table like the following that will give me Seg for the minimized distance (as duplication is seen in ID . Seg Crash_ID Distance Seg46 V21 160.37672 Seg373 V85 167.38930 Seg159 V147 14.74852 Seg233 V171 193

I hope someone can help. I have a large dataset imported to SAS with thousands of variables. I want to create a new dataset by extracting variables that have a specific keyword in their name. For example, the following variables are in my dataset: AAYAN_KK_Equity_Ask AAYAN_KK_Equity_Bid AAYAN_KK_Equity_Close AAYAN_KK_Equity_Date AAYAN_KK_Equity_Volume AAYANRE_KK_Equity_Ask AAYANRE_KK_Equity_Bid AAYANRE_KK_Equity_Close AAYANRE_KK_Equity_Date I want to extract variables that end with _Ask and _Bid without knowing the rest of the variable's name. Is there a way to do that? I want to try using a