Packages
Functionality is maintained in packages. Some packages are part of the basic functionality and are predefined when you install R, others have to be installed (and loaded) before used.
To find out the directories of your packages, enter command .libPaths(), to find the already loaded packages choose search(). The commands installed.packages(), install.packages("..") and update.packages() are self-explaining. To load a package use library(..) or require(..).
To show the content of a package use command help(package="..").
In RStudio this is easy, as you see the packages in an own window.
Data Types
- Scalar A Scalar is a single value vector (numeric, logical or character value) Example: s <- 3="" i="">
- Vector A vector is a collection of scalars of the same type, to combine use c(..) Example: v <- c(1, 2, s, 4, 5, 6, 7, 8) (s from above)
- Matrix A matrix is a collection of vectors, all elements have the same type. Example: m <- matrix(v, nrow=2, ncol=4, byrow = TRUE) (v from above, note that byrow determines if the values of v are filled by row or by column (default)
- Array An Array is a collection of matrices, all elements have the same type. Example: a <- array(v, c(2,2,2))
- DataFrame A data frame is a matrix that can hold different types of elements mixed. As your data will usually be a mix of different types, this is the most used datatype in R. Example: df <- data.frame(column1, colum2, ...) where the columns are vectors of the same length that can be of different type. Fill column names function names(df)=c("x", "y")
- Factor A factor is a nominal (categorical) or ordinal variable (ordered categorical) Example: Yes/No are categorical, Small/Medium/Large/XLarge are ordinal variables
- List A List is a wild collection of other data types. Example: l <- list(s, v, m, a, df) (variables from above). To name it use list("scalar"=s, ...). To access the elements use double brackets and index [[1]] or ["scalar"]
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