Introduction to R

8. Logical operators and functions

Besides the standard format of mathematical notation common to many software (addition is +, subtraction is -, multiplication is *, division is /, and raising to a power is ^), the following list of logical operators is useful.

 

Operator

Meaning

==

Equal to (note it is two equals signs with not space)

!=

Not equal to

Greater than

Less than

>=

Greater than or equal to

<=

Less than or equal to

&

Boolean “and”

Vertical line “|”

Boolean “or”

 

Some other useful mathematical functions are:

Function

Meaning

max(x)

Minimum value

min(x)

Not equal to

sqrt(x)

Square root

ln(x)

Natural logarithm

exp(x)

e raised to the power of x

log(x)

Natural logarithm

log10(x)

Logarithm base 10

abs(x)

Absolute value

round(x)

Round to the nearest whole number

sum(x,y,z)

Sum of x, y and z

 

Note that “x” (or y or z) in the above table could be a number or a variable in the dataframe, for example try max(data$age) to find the maximum age in the dataset.  They can also be combined.  For example, finding the square root of the sum of the ages would be:

sqrt(sum(data$age))

and should return a result of 37.16181