Call a function by using function_name(function_arguments)
apply family of functions: apply(), sapply(), lapply(), and mapply()
apply(dat, MARGIN = 2, mean) will return the average (mean) of each column in dat
Install package by using install.packages("package-name")
Update packages by using update.packages("package-name")
Load packages by using library("package-name")
A value given to a function or program when it runs. The term is often used interchangeably (and inconsistently) with parameter.
A data structure inside a running program that keeps track of active function calls. Each call’s variables are stored in a stack frame; a new stack frame is put on top of the stack for each call, and discarded when the call is finished.
comma-separated values (CSV)
A common textual representation for tables in which the values in each row are separated by commas.
A remark in a program that is intended to help human readers understand what is going on, but is ignored by the computer. Comments in Python, R, and the Unix shell start with a # character and run to the end of the line; comments in SQL start with --, and other languages have other conventions.
A statement in a program that might or might not be executed depending on whether a test is true or false.
dimensions (of an array)
An array’s extent, represented as a vector. For example, an array with 5 rows and 3 columns has dimensions (5,3).
Human-language text written to explain what software does, how it works, or how to use it.
The practice of hiding something’s implementation details so that the rest of a program can worry about what it does rather than how it does it.
A loop that is executed once for each value in some kind of set, list, or range. See also: while loop.
The statements that are executed inside a function.
A use of a function in another piece of software.
The immediate application of one function to the result of another, such as f(g(x)).
A subscript that specifies the location of a single value in a collection, such as a single pixel in an image.
The variable that keeps track of the progress of the loop.
An abstraction of a computer used to think about what it can and will do.
A variable named in the function’s declaration that is used to hold a value passed into the call. The term is often used interchangeably (and inconsistently) with argument.
A connection from the output of one program to the input of another. When two or more programs are connected in this way, they are called a “pipeline”.
A statement that causes a function to stop executing and return a value to its caller immediately.
Failing without producing any warning messages. Silent failures are hard to detect and debug.
A regular subsequence of a larger sequence, such as the first five elements or every second element.
A data structure that provides storage for a function’s local variables. Each time a function is called, a new stack frame is created and put on the top of the call stack. When the function returns, the stack frame is discarded.
standard input (stdin)
A process’s default input stream. In interactive command-line applications, it is typically connected to the keyboard; in a pipe, it receives data from the standard output of the preceding process.
standard output (stdout)
A process’s default output stream. In interactive command-line applications, data sent to standard output is displayed on the screen; in a pipe, it is passed to the standard input of the next process.
Short for “character string”, a sequence of zero or more characters.
A loop that keeps executing as long as some condition is true. See also: for loop.