About
R provides a number of specialized objects. They are created (instantiated), used and referenced through variable (known as symbol).
- When you read the term object in the documentation, you can interchange it with the term variable (known as symbol)
- The variable (known as symbol) are themselves objects
The variable (symbol) references objects.
The symbols are themselves objects and has wide ranging effects.
R have some reserved variable (system variable)
Articles Related
Example
- Numeric
> x=1
# Implicit printing of the variable
> x
[1] 1
# Explicit printing of the variable
> print(x)
The [1] indicates that x is of the vector class
> x+x
[1] 2
Structure
Type
The type determine the internal storage and can be seen as the primitive type of R.
See R - (Datatype|Type|Storage Mode) of an object (typeof, mode)
Class
The class properties permits R to have an object like behavior.
R supports several class (data structure) for an object:
- …. See class
And you can create yours.
Attribute
All objects except the NULL object can have one or more attributes.
Common R objects attributes are:
- the element names,
- dim(ension) attribute (e.g. matrices, arrays)
- dimnames: the size and the name of each dimension of the object
- class which stores the name of the class of the object
- user-defined attributes
- …
Attributes of an object can be listed using the attributes() function.
# data.frame object
x=data.frame(a=1:4,b=1:4,c=1:4)
attributes(x)
$names
[1] "a" "b" "c"
$row.names
[1] 1 2 3 4
$class
[1] "data.frame"
The value of a specific attribute can be obtained using the attr() function (or NULL if the attribute is not defined).
For example,
# data.frame object
x=data.frame(a=1:4,b=1:4,c=1:4)
attr(x, "class")
[1] "data.frame"
Management
Rename
newname <- oldname
rm(oldname)
List
List current objects (objects in the workspace)
ls()
ls shows you the variables
> x <- rnorm(50)
> y <- rnorm(x)
> ls()
[1] "x" "y"
Delete
rm(object)
# Delete all variables for the environment
rm(list = ls())
> rm(x, y)
> ls()
character(0)
Copy
newobject <- edit(object)
Diff
Serialization
Search
apropos (or find) returns a character vector of all objects matching the text searched.
apropos("myObject")
Functions
Structure
Structure of an object
str(object)
Fix / Edit
# Open an editor and doesn't gives the possibility to change the definition
edit(object)
#
# Open an editor and gives the possibility to change the values.
fix(object)
View
View(object)
where object is an object that can be coerced to a data frame