R: The R Project for Statistical Computing

With this module you will learn all the basics to start your Data Science career. The standard (or base) packages are considered part of the Rsource code. They contain the basic functions that allow R to work,and the datasets and standard statistical and graphical functions thatare described in this manual. Without arguments, returns a list of all graphics parameters and theirvalues for the current device. With the Poisson family the default link is the log, and inpractice the major use of this family is to fit surrogate Poissonlog-linear models to frequency data, whose actual distribution is oftenmultinomial. This is a large and important subject we will not discussfurther here.

1.2 Displaying multivariate data ¶

If that fails, andenvironment variables HOMEDRIVE and HOMEPATH are defined(and they normally are) these define the home directory. Failing allthose, the home directory is taken to be the starting directory. Or, via the R CMD interface, as a wrapper to various R tools(e.g., for processing files in R documentation format or manipulatingadd-on packages) which are not intended to be called “directly”. Each new call to a device driver function opens a new graphics device,thus extending by one the device list. This device becomes the currentdevice, to which graphics output will be sent. The value is the desired size of text characters(including plotting characters) relative to the default text size.

Code Game

Create bar plots, histograms, density plots, scatter plots, box plots, … Control whether Rgui will operate as an MDI program (with multiple child windows within one main window) or an SDI application(with multiple top-level windows for the console, graphics and pager). The command-line setting overrides the setting in the user’s Rconsole file. With y to the left of the tilde,we are modelling y dependent on x.

If no .Rprofilefile is found in the startup directory, then R looks for a.Rprofile file in the user’s home directory and uses that (if itexists). If the environment variable R_PROFILE_USER is set, thefile it points to is used instead of the .Rprofile files. As noted above, a matrix is just an array with two subscripts. Howeverit is such an important special case it needs a separate discussion.R contains many operators and functions that are available only formatrices. For example t(X) is the matrix transpose function, asnoted above.

• Note that max and min select the largest and smallestvalues in their arguments, even if they are given several vectors.
• Forces the function to act as a low-level graphics function,superimposing the plot on the current plot (some functions only).
• Among the other generic functions are plot() fordisplaying objects graphically, summary() for summarizinganalyses of various types, and anova() for comparing statisticalmodels.
• Apart from the front-end shell script and the manpage, R installation puts everything (executables, packages, etc.)into this directory.
• Expressions as objects form anadvanced part of R which will not be discussed in this guide, exceptindirectly when we discuss formulae used with modeling in R.
• Convert Rd format to various other formats, including HTML, LaTeX,plain text, and extracting the examples.

Graphical facilities are an important and extremely versatile componentof the R environment. It is possible to use the facilities todisplay a wide variety of statistical graphs and also to build entirelynew types of graph. The names of the standard, supplied family generators are given under“Family Name” in the table in Families. Where there is a choiceof links, the name of the link may also be supplied with the familyname, in parentheses as a parameter.

Packages in R

• The S language is often the vehicle of choice for research in statistical methodology, and R provides an Open Source route to participation in that activity.
• Sometimes the high-level plotting functions don’t produce exactly thekind of plot you desire.
• This section presumes the reader has some familiarity with statisticalmethodology, in particular with regression analysis and the analysis ofvariance.
• The R Journal is an open access, academic journal which features short to medium-length articles on the use and development of R.
• R provides various statistical techniques like statistical tests, clustering and data reduction.
• We recommend reading this tutorial, in the sequence listed in the left menu.

For example, we might wishto split the tax accountants by both state and sex. However in thissimple instance (just one factor) what happens can be thought of asfollows. The values in the vector are collected into groupscorresponding to the distinct entries in the factor. The function isthen applied to each of these groups individually. The value is avector of function results, labelled by the levels attribute ofthe factor. The other recursive structures are those of mode function andexpression.

CRAN Task Views

By the mode of an object we mean the basic type of itsfundamental constituents. Thefunctions mode(object) and length(object) can beused to find out the mode and length of any defined structure11. Elementary commands consist of either expressions orassignments. If an expression is given as a command, it isevaluated, printed (unless specifically made invisible), and the valueis lost.

2 Low-level plotting commands ¶

You can think of setting graphics parameters in this wayas setting “default” values for the parameters, which will be used byall graphics functions unless an alternative value is given. With named arguments (or a single list argument), sets the values ofthe named graphics parameters, and returns the original values of theparameters as a list. Waits for the user to select locations on the current plot using theleft mouse button. This continues until n (default 512) pointshave been selected, or another mouse button is pressed. Thetype argument allows for plotting at the selected points and hasthe same effect as for high-level graphics commands; the default is noplotting. Locator() returns the locations of the points selectedas a list with two components x and y.

The startup procedure under Windows is very similar to that underUNIX, but references to the ‘home directory’ need to be clarified, asthis is not always defined on Windows. If the environment variableR_USER is defined, that gives the home directory. Next, if theenvironment variable HOME is defined, that gives the homedirectory. After those two user-controllable settings, R tries tofind system defined home directories. It first tries to use theWindows “personal” directory (typically My Documents in recent versions of Windows).

It in turn uses the functions qr() and qr.coef()in the slightly counterintuitive way above to do this part of thecalculation. Hence there is probably some value in having just thispart isolated in a simple to use function if it is going to be infrequent use. r&d tax credit If so, we may wish to make it a matrix binary operatorfor even more convenient use. If the second argument is a single value and not a list, a single vectoris read in, all components of which must be of the same mode as thedummy value. By default numeric items (except row labels) are read as numericvariables and non-numeric variables, such as Cent.heat in theexample, as character variables.