R Manipulating Objects

Manipulating Objects

The following commands are used to View objects that are available in the workspace

//Syntax:
	objects()

	ls()

		both the syntax provide the same result

Modify Objects

edit() function will invokes a text editor on an R object

• edit() works with any type of object
  • Vector
  • List
  • Matrix
  • Data Frame
  • Factor

Consider an object newData

edit(newData) invokes an editor in which the data can be modified. The example shown illustrates the same

modData <- edit(newData)

Data Editor window will pop up and data can be edited in the same window. For vectors, lists and factors, a notepad will pop up.

append() function adds elements to a vector

//Syntax:
	append(x, value, after = length(x))
	
		Where,
			x: the vector
			value: the value to be appended

	after: the position after which the element has to be appended

newVar <- c(11,25,32,22,44,25,43,22)
	append(newVar, 99, after = 4)
	[1] 11 25 32 22 99 44 25 43 22

	append(newVar, 99, after = 5)
	[1] 11 25 32 22 44 99 25 43 22

The value is placed, based on the position in the syntax Additional elements can be appended at the end of an object by using the concatenation command c()

x <- 1:10
	x
	[1] 1 2 3 4 5 6 7 8 9 10

	x <- c(x, 11:20)
	x
	[1] 1 2 3 4 5 6 7 8 9 10
	[11] 11 12 13 14 15 16 17 18 19 20

# The values will be appended at the end

An element can be removed from an object by prefixing its index position with the minus (‘-’) symbol

#removing 11 from x
	x <- x[-11]
	print(x)

	[1] 1 2 3 4 5 6 7 8 9 
	[10] 10 12 13 14 15 16 17 18 19
	[19] 20

Delete Objects

remove() and rm() can be used to remove objects. These can be specified successively as character strings or in the character vector list or through a combination of both. All objects thus specified will be removed

Consider the following objects in R

ls()
	[1] "a" "b" "c" "d" "newData" "trees"

If we want to delete ‘b’ and ‘trees’ objects

rm("b", "trees")
	ls()
	[1] "a" "c" "d" "newData"

If we want to remove all the objects in R, use rm(list =ls())

rm(list=ls())

	#Now lets check, by using ls() command
	ls()
	[1] character(0)

All the objects created can be saved and accessed later by using save.image() and load() functions

#Consider a matrix Object ‘x’
	x
	Jane Tom Katy James
	[1,] 99.0 99.8 99.4 98.3
	[2,] 96.0 98.3 99.2 99.1
	[3,] 99.2 99.7 98.9 99.9

	#Saving the existing objects
	setwd("D:/R/")
	save.image(file = "saveObjects.RData")

	#Now lets delete this object
	rm(x)

	#Check if the object exists
	print(x)
	Error in print(x) : object ‘x’ not found

	#Now lets get the value back
	load(file = "saveObjects.RData")

	#Check if the object x exists
	print(x)
	Jane Tom Katy James
	[1,] 99.0 99.8 99.4 98.3
	[2,] 96.0 98.3 99.2 99.1
	[3,] 99.2 99.7 98.3 99.9

When saving the file, extension must be “.RData”