# What is your favorite R feature?

(This article was first published on cloudnumbers.com » R-project, and kindly contributed to R-bloggers)

R (www.r-project.org) is a free and strongly functional language and environment for statistical computing. You can explore data sets, make graphical displays of data, run statistical simulations and many more. If you never used R you should give it a try!

R beginners:
There are many courses, slides and tutorials available for R beginners. We are not planning to add another one to this list. Here we provide you with an incomplete list of nice R beginners sessions. You can also follow our list of nice R features, start the preinstalled R at cloudnumbers.com, copy and paste the following commands into the cloudnumbers.com’s web console and enjoy the diversity of R.

Nice R features:

R as a calculator:
R provides you with all functionality of a powerful pocket calculator. All standard functions (powers, exponential, squareroot, logarithm, etc.) are built-in. Here are some examples:

``` (17-3) / (3-1) + 1 3*4 - 7 + 1.5 1.8^2 * exp(0.5) - sqrt(2.4) ```

You can also assign values to variables and use them for later computations:

``` x <- 1.8^2 y <- exp(0.5) z <- x*y - sqrt(2.4) z ```

R for visualization:
R is an environment for statistical computing and graphics! Draw star plots or segment diagrams of a multivariate data set “mtcars” (default data set in R).

``` palette(rainbow(12, s = 0.6, v = 0.75)) mtcars stars(mtcars[, 1:7], len = 0.8, key.loc = c(12, 1.5), main = "Motor Trend Cars", draw.segments = TRUE) ```

Another nice example is the “The Maunga Whau Volcano plot”. A contour plot using heat colors. The dataset volcano is one of the default datasets in R.

``` volcano x <- 10*(1:nrow(volcano)); x.at <- seq(100, 800, by=100) y <- 10*(1:ncol(volcano)); y.at <- seq(100, 600, by=100) # Using Terrain Colors image(x, y, volcano, col=terrain.colors(100),axes=FALSE) contour(x, y, volcano, levels=seq(90, 200, by=5), add=TRUE, col="brown") axis(1, at=x.at) axis(2, at=y.at) box() title(main="Maunga Whau Volcano", sub = "col=terrain.colors(100)", font.main=4) ``` More very nice R plots including example code and data are available in the R graph gallery.

R help system:
R provides you with a very flexible help system. You can search for help inside all loaded packages using the command help() or use the simple question mark command “?commandName”. Here are some examples:

``` help(lm) ?lm ?"for" ?"[[" args("lm") ?volcano help.search("regression") RSiteSearch("cloudnumbers.com") ```

We will come up with the second part of our favorite R features at the end of the week: R programming, libraries and statistical analyses, biological data analyses with Bioconductor and high-performance computing with R.

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