Integer vs. Double

The two most common numeric classes used in R are integer and double (for double precision floating point numbers). R automatically converts between these two classes when needed for mathematical purposes. As a result, it’s feasible to use R and perform analyses for years without specifying these differences.

Creating Integer and Double Vectors

By default, when you create a numeric vector using the c() function it will produce a vector of double precision numeric values. To create a vector of integers using c() you must specify explicity by placing an L directly after each number.

# create a string of double-precision values
dbl_var <- c(1, 2.5, 4.5)  
dbl_var
## [1] 1.0 2.5 4.5

# placing an L after the values creates a string of integers
int_var <- c(1L, 6L, 10L)
int_var
## [1]  1  6 10

Checking for Numeric Type

To check whether a vector is made up of integer or double values:

# identifies the vector type (double, integer, logical, or character)
typeof(dbl_var)
## [1] "double"

typeof(int_var)
## [1] "integer"

Converting Between Integer and Double Values

By default, if you read in data that has no decimal points or you create numeric values using the x <- 1:10 method the numeric values will be coded as integer. If you want to change a double to an integer or vice versa you can specify one of the following:

# converts integers to double-precision values
as.double(int_var)     
## [1]  1  6 10

# identical to as.double()
as.numeric(int_var)    
## [1]  1  6 10

# converts doubles to integers
as.integer(dbl_var)         
## [1] 1 2 4