Hi Michael,
Thanks for your answer! sorry I didn't see this rule... No problem,
I'll try to figure it out by myself.
Thanks for your indication though!
Thomas
2012/1/4, Michael Weylandt [via R] <ml-node+s789695n4261894...@n4.nabble.com>:
>
>
> Unfortunately, there's a general no-homework rule because we never
> know what your instructor wants you to figure out on your own (though,
> a sincere thanks for admitting this was hw rather than trying to trick
> us like so many). That said, I think your second function, while a
> little clumsy, does work but for one little error near the end. It's
> very obvious when you see it so don't overthink it, but look closely
> at the lines that involve "swap".
>
> If you want to make it more elegant, I'd suggest you look at the
> ?switch construct: also, to make the swap bit more elegant, think
> about how one exchanges variable values in a language like C and put
> some construct like that within an "if" statement near the top. If you
> want to get real elegant, note that after you figure out switch,
> constructs like `+`(3, 4) are valid in R (though certainly beyond the
> scope of your exercise)
>
> Hope this helps,
>
> Michael
>
> On Wed, Jan 4, 2012 at 9:45 AM, Thomthom <rime.tho...@gmail.com> wrote:
>> Hi R helpers!
>>
>> I have a question. I'm trying to create a function for an exercise. Here
>> are
>> the arguments I should include:
>>
>> x and y are numeric
>> z is a name ("plus","minus","multiply","divide")
>> and swap is logical.
>>
>> Here is what the function should do:
>>
>> When z="plus", then x+y is performed and so on for the other z names. It
>> should give a NA when the z argument doesn't correspond to something
>> mention
>> before.
>> When swap =TRUE, then y must be on the left side of the equation (y/x
>> instead of x/y).
>>
>> So far, I managed to get something worked for the first part of the body
>> function (typing "plus" performes indeed an addition...) but I couldn't
>> get
>> how to make the second part working. Any suggestion?
>>
>> Here is the code I have so far:
>>
>> myFunc<- function(x,y,z,swap)
>> Â Â Â Â Â Â Â Â { res= NULL
>> Â Â Â Â Â Â Â Â Â if(z =="plus") res=x+y
>> Â Â Â Â Â Â Â Â Â else if(z=="minus") res=x-y
>> Â Â Â Â Â Â Â Â Â else if(z== "multiply") res=x*y
>> Â Â Â Â Â Â Â Â Â else if(z=="divide") res=x/y
>> Â Â Â Â Â Â Â Â Â else res<-NA
>>
>> Â Â Â Â Â Â Â Â Â return(res)}
>>
>> Then, I tried to include some lines to take this "swap" function into
>> account by "splitting" somehow my function in 2:
>>
>> myFunc<- function(x,y,z,swap)
>> Â Â Â Â Â Â Â Â { res1= NULL
>> Â Â Â Â Â Â Â Â Â res2=NULL
>>
>> Â Â Â Â Â Â Â Â Â if(z =="plus") res1=x+y
>> Â Â Â Â Â Â Â Â Â else if(z=="minus") res1=x-y
>> Â Â Â Â Â Â Â Â Â else if(z== "multiply") res1=x*y
>> Â Â Â Â Â Â Â Â Â else if(z=="divide") res1=x/y
>> Â Â Â Â Â Â Â Â Â else res1<-NA
>>
>> Â Â Â Â Â Â Â Â Â if(z =="plus") res2=y+x
>> Â Â Â Â Â Â Â Â Â else if(z=="minus") res2=y-x
>> Â Â Â Â Â Â Â Â Â else if(z== "multiply") res2=y*x
>> Â Â Â Â Â Â Â Â Â else if(z=="divide") res2=y/x
>> Â Â Â Â Â Â Â Â Â else res2<-NA
>>
>> Â Â Â Â Â Â Â Â Â if (swap<-T) return(res2)
>> Â Â Â Â Â Â Â Â Â else return(res1)
>> Â Â Â Â Â Â Â }
>> Any suggestions would be more than appreciated! I already thank you!
>>
>> And happy new year! (that may be redundant to most of you I know ^^)
>>
>> Thomas
>>
>> --
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>>
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