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Comparison of apply() versus for-loop in 3 versions of R
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| ############################################################################ | |
| R version 2.5.0 (2007-04-23) | |
| Copyright (C) 2007 The R Foundation for Statistical Computing | |
| ISBN 3-900051-07-0 | |
| R is free software and comes with ABSOLUTELY NO WARRANTY. | |
| You are welcome to redistribute it under certain conditions. | |
| Type 'license()' or 'licence()' for distribution details. | |
| Natural language support but running in an English locale | |
| R is a collaborative project with many contributors. | |
| Type 'contributors()' for more information and | |
| 'citation()' on how to cite R or R packages in publications. | |
| Type 'demo()' for some demos, 'help()' for on-line help, or | |
| 'help.start()' for an HTML browser interface to help. | |
| Type 'q()' to quit R. | |
| > n <- 2000 | |
| > x <- matrix(runif(n*n), nrow=n, ncol=n) | |
| > | |
| > f1 <- function(x) { | |
| + nr <- nrow(x) | |
| + m <- rep(NA_real_, nr) | |
| + for (i in 1:nr) { | |
| + m[i] <- mean(x[i,]) | |
| + } | |
| + return(m) | |
| + } | |
| > f2 <- function(x) apply(x, 1, mean) | |
| > f3 <- function(x) rowMeans(x) | |
| > | |
| > system.time(replicate(100, f1(x))) | |
| user system elapsed | |
| 5.659 0.015 5.677 | |
| > system.time(replicate(100, f2(x))) | |
| user system elapsed | |
| 8.363 0.016 8.380 | |
| > system.time(replicate(100, f3(x))) | |
| user system elapsed | |
| 0.725 0.000 0.725 | |
| ############################################################################ | |
| R version 3.0.0 (2013-04-03) -- "Masked Marvel" | |
| Copyright (C) 2013 The R Foundation for Statistical Computing | |
| Platform: x86_64-unknown-linux-gnu (64-bit) | |
| R is free software and comes with ABSOLUTELY NO WARRANTY. | |
| You are welcome to redistribute it under certain conditions. | |
| Type 'license()' or 'licence()' for distribution details. | |
| Natural language support but running in an English locale | |
| R is a collaborative project with many contributors. | |
| Type 'contributors()' for more information and | |
| 'citation()' on how to cite R or R packages in publications. | |
| Type 'demo()' for some demos, 'help()' for on-line help, or | |
| 'help.start()' for an HTML browser interface to help. | |
| Type 'q()' to quit R. | |
| > n <- 2000 | |
| > x <- matrix(runif(n*n), nrow=n, ncol=n) | |
| > | |
| > f1 <- function(x) { | |
| + nr <- nrow(x) | |
| + m <- rep(NA_real_, nr) | |
| + for (i in 1:nr) { | |
| + m[i] <- mean(x[i,]) | |
| + } | |
| + return(m) | |
| + } | |
| > f2 <- function(x) apply(x, 1, mean) | |
| > f3 <- function(x) rowMeans(x) | |
| > | |
| > system.time(replicate(100, f1(x))) | |
| user system elapsed | |
| 5.069 0.000 5.070 | |
| > system.time(replicate(100, f2(x))) | |
| user system elapsed | |
| 7.561 0.008 7.570 | |
| > system.time(replicate(100, f3(x))) | |
| user system elapsed | |
| 0.724 0.000 0.725 | |
| ############################################################################ | |
| R version 4.2.0 (2022-04-22) -- "Vigorous Calisthenics" | |
| Copyright (C) 2022 The R Foundation for Statistical Computing | |
| Platform: x86_64-pc-linux-gnu (64-bit) | |
| R is free software and comes with ABSOLUTELY NO WARRANTY. | |
| You are welcome to redistribute it under certain conditions. | |
| Type 'license()' or 'licence()' for distribution details. | |
| Natural language support but running in an English locale | |
| R is a collaborative project with many contributors. | |
| Type 'contributors()' for more information and | |
| 'citation()' on how to cite R or R packages in publications. | |
| Type 'demo()' for some demos, 'help()' for on-line help, or | |
| 'help.start()' for an HTML browser interface to help. | |
| Type 'q()' to quit R. | |
| > n <- 2000 | |
| > x <- matrix(runif(n*n), nrow=n, ncol=n) | |
| > | |
| > f1 <- function(x) { | |
| + nr <- nrow(x) | |
| + m <- rep(NA_real_, nr) | |
| + for (i in 1:nr) { | |
| + m[i] <- mean(x[i,]) | |
| + } | |
| + return(m) | |
| + } | |
| > f2 <- function(x) apply(x, 1, mean) | |
| > f3 <- function(x) rowMeans(x) | |
| > | |
| > system.time(replicate(100, f1(x))) | |
| user system elapsed | |
| 4.915 0.020 4.936 | |
| > system.time(replicate(100, f2(x))) | |
| user system elapsed | |
| 5.072 0.036 5.108 | |
| > system.time(replicate(100, f3(x))) | |
| user system elapsed | |
| 0.635 0.000 0.635 | |
| ############################################################################ |
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