is.data type is used to test the data type of a data object.
If the data object is a data type object, where data type is any
of the data types listed below, is.data type returns TRUE, and returns
FALSE otherwise.as.data type changes the data type of a data object.
Both is. and as. can be used for the following data types (with the exception of na which can only be used with is.):
array Multi-Way Arrays
category Category
character Character objects
complex Complex Valued objects
double Double Precision objects
factor Factor objects
function Function objects
integer Integer objects
list List objects
logical Logical objects
matrix Matrix objects
na NA
name Name objects
null Null objects
numeric Numeric objects
single Single Precision objects
ts Time Series objects
vector Vectors
> age_c("10","18","76","65","32")
> age
[1] "10" "18" "76" "65" "32"
> age + 10
Error in age + 10: Non-numeric first operand
Dumped
> is.numeric(age)[1] F
> age_as.numeric(age)
> age [1] 10 18 76 65 32 > age + 10 [1] 20 28 86 75 42 > x_c(1,2,3,NA) > is.na(x) [1] F F F T