In R, arithmetic operations on vectors occur
element-wise. For example, we have a vector say height in inches and suppose
we want to convert them to centimeters , then we multiply the heights vector
with 2.54 as show below and the resultant vector shows the heights in
centimeters.
> heights <-
c(69,62,66,70,70,73,67,73,67,70)
>heights*2.54
Similarly we can perform other operations
like subtraction, addition , division etc. The elementary arithmetic operators are the usual +, -, *, / and ^ for
raising to a power. In
addition all of the common arithmetic functions are available. log, exp, sin, cos, tan, sqrt,
and so on, all have their usual meaning. max and min select the
largest and smallest elements of a vector respectively. range is a function whose value is a vector of length
two, namely c(min(x), max(x)).length(x) is
the number of elements in x, sum(x) gives
the total of the elements in x, and prod(x) their
product.If we have two vectors of same length, these operations are more
powerful .The operator used (+ , - , / etc) is applied entry by entry in these
two vectors .
Vectors occurring in the same expression need
not all be of the same length. If they are not, the value of the expression is
a vector with the same length as the longest vector which occurs in the
expression.Suppose we have a dataset showing the murders per state and the
population of that state , to calculate the murder rate(murders for every
100,000 people) for each state all we have to do is:
>murder_rate <-
murders$total/murders$population * 100000
We can use these tools to analyze murder rate
of all the states, the average murder rate in a country and see which states
are safer by applying the sort functions.Refer the R-Manual for documentation on arithmetic operators and their usage .
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