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R Programming Course Johns Hopkins University

Users can customize their environment in several different ways. Thereis a site initialization file and every directory can have its ownspecial initialization file. So far we have compared a single sample to a normal distribution. Amuch more common r & d accounting operation is to compare aspects of two samples. Notethat in R, all “classical” tests including the ones used below arein package stats which is normally loaded.

Arrays

• A 1 stands for anintercept column and is by default included in the model matrix unlessexplicitly removed.
• The standard (or base) packages are considered part of the Rsource code.
• Although this is doneautomatically, it may useful to know that the command used isX11() under UNIX, windows() under Windows andquartz() under macOS.
• Apart from the front-end shell script and the manpage, R installation puts everything (executables, packages, etc.)into this directory.

In some cases the components of a vector may not be completelyknown. Themotivation for this rule is simply that if the specification of anoperation is incomplete, the result cannot be known and hence is notavailable. Logical vectors https://www.facebook.com/BooksTimeInc/ may be used in ordinary arithmetic, in which case theyare coerced into numeric vectors, FALSE becoming 0and TRUE becoming 1.

• Technically R is an expression language with a very simplesyntax.
• For simple vectors this is just the mode, for example”numeric”, “logical”, “character” or “list”,but “matrix”, “array”, “factor” and”data.frame” are other possible values.
• Amuch more common operation is to compare aspects of two samples.
• Control statements are most often used in connection withfunctions which are discussed in Writing your own functions, and where more examples will emerge.
• If Lst is a list, then the function length(Lst) gives thenumber of (top level) components it has.
• Returns the variance-covariance matrix of the main parameters of afitted model object.

3 Generic functions for extracting model information ¶

Sometimes the high-level plotting functions don’t produce exactly thekind of plot you desire. In this case, low-level plotting commands canbe used to add extra information (such as points, lines or text) to thecurrent plot. Df is a data frame, y is any object, expr is a listof object names separated by ‘+’ (e.g., a + b + c). Thefirst two forms produce distributional plots of the variables in a dataframe (first form) or of a number of named objects (second form). In the latter case the variance functionmust be specified as a function of the mean, but in other cases thisfunction is implied by the response distribution. The class mechanism offers the userthe facility of designing and writing generic functions for specialpurposes.

8 Customizing the environment ¶

When multiple devices are open, https://www.bookstime.com/articles/quicken-bookkeeping they form anumbered sequence with names giving the kind of device at any position. Without arguments, returns a list of all graphics parameters and theirvalues for the current device. The par() function is used to access and modify the list ofgraphics parameters for the current graphics device. The first formgenerates a bar plot of f; the second form produces boxplots ofy for each level of f. For quasi-likelihood estimation and inference the precise responsedistribution is not specified, but rather only a link function and theform of the variance function as it depends on the mean.

The entities R operates on are technically known as objects.Examples are vectors of numeric (real) or complex values, vectors oflogical values and vectors of character strings. These are known as“atomic” structures since their components are all of the same type,or mode, namely numeric10, complex,logical, character and raw. The entities that R creates and manipulates are known asobjects. These may be variables, arrays of numbers, characterstrings, functions, or more general structures built from suchcomponents. Technically R is an expression language with a very simplesyntax.