 # Function that returns multiple values

Hi everyone,

I could really use your help! I'm very new to R Studio and I love it! But, I am trying to solve two issues:

1. I need to create a function that can take in a few values (x, y, z) and solve for the mean, minimum, maximum, and std. deviation. However, my code does not work and this is what I have.
StatCount<- function(x, y, z)
{ a<- mean(x, y, z)
b<- x[which.max(x, y, z)]
c<- x[which.min(x, y, z)]
d<- sd(x, y, z)
return(a);
return(b);
return(c);
return (d);
}
The error given says that "multi-argument returns are not permitted"

2. My second request is this: "In statistics, a dataset needs to be transformed in order to meet certain assumptions. Write a custom R function that takes any univariate dataset and creates a histogram of the raw dataset and a histogram of the log-transformed dataset."

How on earth can you take a random variable that is a dataset that is passed to a function to automatically generate a histogram?! Help!

Aerianna

A function can only return one thing but that thing can be a multi element object like a vector or a list. Think along these lines

``````StatCount <- function(x, y, z) {
... calculations go here...
return c(MEAN = a, MAX = b, MIN = c, SD = d)
``````

This is obviously homework so I do not want to just give you the answer. How to the second part. How would you produce a histogram outside of a function? How would you produce a function of the log-transformed values? Very little about the task will be different inside of function except that the data set will be passed in as an argument to the function.

First of all, I really appreciate your help. As to the first part, I don't understand the reasoning of:

return c(MEAN = a, MAX = b, MIN = c, SD = d)

What does "c" represent? Because "c" has been assigned to the Min value. But, if I remove the "c" value for the return statement I get this:
Error in return(Mean = a, Max = b, Min = c, SD = d) :
multi-argument returns are not permitted

The second issue... I can definitely make a histogram with any given dataset. But if a dataset is unknown, how do you pass a random dataset into a function? Would it just be GraphData<- function(dataset) {.....} ?

`c` is a function that combines values into a vector. For example:

``````x = c(3, 10, 11)
y = c("yes", "no", "maybe")
``````

Run `?c` to bring up the help file for the `c` function.

But you can also use `c` as the name of an object, like a vector, list, or data frame (although you probably shouldn't to avoid confusion). For example:

``````a = 5
b = 6
c = 7
``````

And you can then put these into a vector using the `c` function:

``````x = c(a, b, c)

x
#  5 6 7
``````

Using `c` as both a function and the name of an R object works because when you call a function (like `c`), R evaluates the function call by searching only for a function named `c` and ignores objects named `c` that aren't functions (see this StackOverflow answer for additional information).

Likewise, many people call their data frame `df`, as in:

``````df = data.frame(x=1:5, y=6:10)
``````

But there is also an R function called `df` (the density function of the F distribution; for example `df(seq(0,3,length=20), 20, 50)`). Most people rarely need to use the `df` function, so naming a data frame `df` doesn't usually cause confusion. But `c` is used frequently, so it's probably best to avoid calling an object (like a vector, list, or data frame) `c`.

1 Like

I think you have the right idea. The code above will produce a function called GraphData with an argument named dataset. If you then have some data named MyData, you can call

``````GraphData(MyData)
``````

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