由于parallel创建的是套接字集群,这使得将并行任务分配至多台计算机成为可能。当然这并不意味着计算机越多就能获得更快的计算速度。parallel分配任务的方式类似均分,如果计算机之间单核的性能差距过大,那么会出现一台计算机分配的任务已经完成而等待其他计算机的现象,这样反而会出现计算速度的下降。并且并行计算的速度还与计算机之间
# after vectorization and pre-allocation,taking thecondition checking outside the loop.output<-character(nrow(df))#预分配初始化向量 condition<-(df$col1+df$col2+df$col3+df$col4)>4# condition check outside the loop system.time({for(i in1:nrow(df)){if(condition[i]){output[i]<-"great...
R 语言中的条件语句（if-else）和 C 语言中类似此处就不再介绍，循环语句包括 for 和 while 控制块。
解决方法:考虑使用向量化操作或并行计算包(如parallel)来提高性能。 示例代码:解决向量长度不匹配问题 代码语言:txt 复制 # 错误示例:动态添加元素导致长度不匹配 squares <- c() for (i in 1:10) { squares <- c(squares, i^2) # 效率低下且容易出错 } # 正确示例:预先分配向量长度 squares <- numeric...
mapply is a multivariate apply of sorts which applies a funtion in parallel over a set of arguments. 比如lapply 是对一个list 进行1个function的循环操作,而mapply就是对多个list进行操作,并且针对每个list的function都可以是不一样的。(mapply 的功能也可以通过for 来实现) mapply(rep,1:4,4:1) ## re...
(500, 2000, 500)) # Register parallel cores doParallel::registerDoParallel(4) # train model set.seed(123) tune_fit <- train( Group ~., data = trainData, method = customRF, #"rf", trControl = myControl, tuneGrid = tuneGrid, metric = "Accuracy", verbose = FALSE) ...
M. Griebl and C. Lengauer. The loop parallelizer LooPo--Announcement. In Proc. Int'l Workshop Languages and Compilers for Parallel Computing (LCPC), volume 1239 of LNCS, pages 603-604. Springer, 1997.Martin Griebl and Christian Lengauer. The loop parallelizer loopo - announce- ment. ...
The ESS (Emacs Speaks Statistics) package is an add-on for Emacs that allows you to run R directly within Emacs. For more on this project, seehttp://ess.r-project.org/ 第三章 数据结构介绍 向量是最简单的数据结构,数组是一个多维向量,矩阵是一个二维数据; ...
Consequently, the NTS is positioned parallel to the guide RNA–TS DNA heteroduplex within the central binding channel (Fig. 1b). The 5′-terminal part of the sgRNA appears to be conformationally flexible but residual cryo-EM density suggests its placement in a positively charged cleft located ...
mapply is a multivariate apply of sorts which applies a function in parallel over a set of arguments. > str(mapply) function (FUN, ..., MoreArgs = NULL, SIMPLIFY = TRUE,USE.NAMES = TRUE) FUN is a function to apply ... contains arguments to apply over MoreArgs is a list of other...