[R] Function argument and scope

[Bernardo Doré]

Thank you all for replying so quickly.

@Jim
You are right, I ran into that. You can see as.character() being called to
remedy the situation you described. I dropped the factors from the data
frame in a line outside the function. Creating the dataframe with
stringsAsFactors = F is the easiest way to go. Tks.

@Thomas, @Jeremiah
R really creates a copy and forgets the reference. That was clearly visible
in the debugger. In an earlier version of this I was returning a list of
the compute values. I will go back to that.

Tks a lot for helping me with this.

Bernardo Doré



>
> On Sun, Nov 13, 2016 at 2:09 PM, Bernardo Doré <berdore at gmail.com> wrote:
>
>> Hello list,
>>
>> my first post but I've been using this list as a help source for a while.
>> Couldn't live without it.
>>
>> I am writing a function that takes a dataframe as an argument and in the
>> end I intend to assign the result of some computation back to the
>> dataframe. This is what I have so far:
>>
>> myFunction <- function(x){
>>   y <- x[1,1]
>>   z <- strsplit(as.character(y), split = " ")
>>   if(length(z[[1]] > 1)){
>>     predictedWord <- z[[1]][length(z[[1]])]
>>     z <- z[[1]][-c(length(z[[1]]))]
>>     z <- paste(z, collapse = " ")
>>   }
>>   x[1,1] <- z
>> }
>>
>> And lets say I create my dataframe like this:
>> test <- data.frame(var1=c("a","b","c"),var2=c("d","e","f"))
>>
>> and then call
>> myFunction(test)
>>
>> The problem is when I assign x[1,1] to y in the first operation inside the
>> function, x becomes a dataframe inside the function scope and loses the
>> reference to the dataframe "test" passed as argument. In the end when I
>> assign z to what should be row 1 and column 1 of the "test" dataframe, it
>> assigns to x inside the function scope and no modification is made on
>> "test".
>>
>> I hope the problem statement is clear.
>>
>> Thank you,
>>
>> Bernardo Doré
>>
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>>
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>
>
>

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