Pythagorean Theorem in R programming - r

Question

I want write R code for Pythagoras theorem.
The Pythagorean Theorem states that the square of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the other two sides.
(sideA)^2+(SideB)^2=hypotenuse^2
Now I wrote the R code as below:
pythag<-function(sidea,sideb){
if (sidea>=0&sideb>=0)
hypoteneuse=sqrt(sidea^2+sideb^2)
else if (sidea<0|sideb<0)
hypoteneuse<-"Values Need to be Positive"
else if (!is.vector(x))
hypoteneuse<-"I need numeric values to make this work"
print(hypoteneuse)
}
pythag(4,5)
pythag("A","B")
pythag(-4,-5)
In case of pythag(4,5) it is ok, also pythag(-4,-5) is giving comment "Values Need to be Positive".
But in case of pythag("A","B") I want comment "I need numeric values to make this work", but unfortunately my code does't work for this.

Answer 1

You can try like this:
get_hypotenuse_length <- function(height, base)
{
sides <- c(height, base)
if(any(sides < 0))
{
message("sides must be positive")
} else if(!is.numeric(x = sides))
{
message("sides can not be non-numeric")
} else
{
sqrt(x = sum(sides ^ 2))
}
}

Answer 2

Here's an annotated version. It is creating the function which takes the values a and b and calculates c. It is first testing if the values are numeric, if they are not numeric it will print your error message, otherwise it will ignore what is within those curly brackets and move on to the next test. The second test is checking that both are greater than zero (seeing as a triangle can't have a side of length zero or negative length). If it satifies the condition that both are >0 then it will calculate c, if not it will give the error stating that there are negative values.
# Feed it the values a and b (length of the two sides)
pythag <- function(a,b){
# Test that both are numeric - return error if either is not numeric
if(is.numeric(a) == FALSE | is.numeric(b) == FALSE){
return('I need numeric values to make this work')}
# Test that both are positive - return length of hypoteneuese if true...
if(a > 0 & b > 0){
return(sqrt((a^2)+(b^2)))
}else{
# ... give an error either is not positive
return('Values Need to be Positive')
}
}
Here's a more streamlined version:
pythag <- function(a,b){
if(is.numeric(a) == FALSE | is.numeric(b) == FALSE){return('I need numeric values to make this work')}
if(a > 0 & b > 0){return(sqrt((a^2)+(b^2)))}
else{return('Values Need to be Positive')}
}
And this is what it returns with your examples:
> pythag(4,5)
[1] 6.403124
> pythag("A","B")
[1] "I need numeric values to make this work"
> pythag(-4,-5)
[1] "Values Need to be Positive"

Answer 3

if x = c("sideA", "sideB"), then it will still be a vector so your test is.vector(x) will return true:
> is.vector(x)
[1] TRUE
But you want to test if it's numbers, so if it's numeric:
> is.numeric(x)
[1] FALSE