Data types in R-Language

Like any other language, R also provides with following data types:

• Numeric (something similar to float)
• Integer
• Character (same as string and array of string)
• Logical (same as boolean)
• Complex (as we studied in school, a + ib)
• Factors
• List

Assignments of variables

There are two types: + One is the direct assignment, may also be called as primitives

x = 34

Such assignments always make numeric variable. To check variable type, just write class(x)

x = as.integer(3.4)

This will make 3.4 explicitly being treated as integer, therefore, .4 will be truncated

x = "Vineet Maheshwari"

Assigns character (or string in regular language)

One can coerce a variable into other type, typically required between integers and float. It can be done by:

x = 4
y = as.integer(x)
class(x)
class(y)

• Another one is using the vector and making the variables it’s components (or members in routine language). ‘c’ is the function call used, i understand, refers to “component”, nevertheless, it is good to settle question on what “c” stands for.

x = c(23,TRUE, "Vineet")
class(x)
x

Note in the output of above following:

a. class outputs again type as “character”

b. x has coerced all components to “character”

Playing with vectors

Combining them

We can combine them just like we created vector.

x = "Vineet"
y = c("Maheshwari", ",", 5.6, ",Gurgaon")
z = c(x, " ", y)
z
[1] "Vineet"     " "          "Maheshwari" ","          "5.6"       
[6] ",Gurgaon"
>

You can measure the length of this vector to verify

length(z)
[1] 6
>

Checkout coercion once again

> a = c(1,2,3)
> a
[1] 1 2 3
> b = c(a, "Vineet")
> b
[1] "1"      "2"      "3"      "Vineet"

Note here the way integer array is converted to array of strings. This means, R wants all members to be of same type

Doing some maths

Same symbols +, -, *, / are used to perform maths. However, if we operate to a vector, it follows following rules: + if it is single item, than it is operated upon all the members/components + if it is again a vector than it adds index by index + if it is unequal in size, than the elements from smaller one are reused

> a = c(1,2,3)
> a
[1] 1 2 3
> a + 2
[1] 3 4 5
> 
> b = c(3,3,10)
> b
> [1]  3  3 10
> a
[1] 1 2 3
> b+a
[1]  4  5 13
> b
[1]  3  3 10
> c = c(12,13)
> b+c
[1] 15 16 22
Warning message:
In b + c : longer object length is not a multiple of shorter object length
>

Note 12 is added again to 10. This is also known as recycling.

Accessing the members

Like arrays in C, one can do the same here. Also, it has adopted the convenience displayed in other languages like PHP, Python

> b
[1]  3  3 10
> b[3]
> 10
>

Note that 0 is special index. It contains the type of the vector, in this case it is numeric.

Use can access members with pair of integer indexes separated by :

> a
[1] 1 2 3
> a[2:3]
[1] 2 3
>

New ways

####Use Negative Index here is use of -ve index. It removes that indexed member which is stated like this. > b[-2] [1] 3 10 > Note: 2nd component removed.

Use list of indexes

Another one, instead of integer index, give another vector, with list of integer indexes. These index values can repeat. R shall return whatever is rquested from here.

> s = c("Ram", "Venkat", "Shree")
> s[c(1,1,1)]
[1] "Ram" "Ram" "Ram"

Use list of logical values

It is like a switch, placed on top of all members in given vector. If it is “True”, i.e. “On”, it will show up in final outcome, else not.

> a
[1] 1 2 3
> a[c(TRUE,FALSE,FALSE)]
[1] 1
>

Labelling vector members

Use names() function to create another array of labels for the given vector. Usage is as:

> person1 = c("Vineet", "Maheshwari", 5.5, "Gurgaon")
> names(person1) = c("First Name", "Last Name", "Height", "City")
> person1
  First Name    Last Name       Height         City 
    "Vineet" "Maheshwari"        "5.5"    "Gurgaon" 
>

Note here, the function being used is on the LHS, with argument as the target vector.