[R] Choosing a column for analysis in a function

Adaikalavan Ramasamy ramasamy at cancer.org.uk
Thu May 31 15:56:59 CEST 2007


Perhaps the use of as.character() like following might help?

  data.whole$Analyte.Values <- data.whole$as.character(analyte)


Junnila, Jouni wrote:
> Hello all,
> 
> I'm having a problem concerning choosing columns from a dataset in a
> function.
> 
> I'm writing a function for data input etc., which first reads the data,
> and then does several data manipulation tasks. 
> The function can be then used, with just giving the path of the .txt
> file where the data is being held. 
> 
> These datasets consists of over 20 different analytes. Though,
> statistical analyses should be made seperately analyte by analyte. So
> the function needs to be able to choose a certain analyte based on what
> the user of the function gives as a parameter when calling the function.
> The name of the analyte user gives, is the same as a name of a column in
> the data set.
> 
> The question is: how can I refer to the parameter which the user gives,
> inside the function? I cannot give the name of the analyte directly
> inside the function, as the same function should work for all the 20
> analytes.
> I'm giving some code for clarification:
> 
>> datainput <- function(data1,data2,data3,data4,data5,data6,analyte)
>> {
> ...
> ##data1-data6 being the paths of the six datasets I want to combine and
> analyte being the special analyte I want to analyze and which can be
> found on each of the datasets as a columnname.##
> ##Then:##
> ...
>> data.whole <- subset(data.whole,
> select=c(Sample.Name,Analyte.Values,Day,Plate))
> 
> ##Is for choosing the columns needed for analysis. The "Analyte" should
> now be the column of the analyte, the users is referring to when calling
> the datainput-function. How to do it? ## 
> I've tried something like
>> data.whole$Analyte.Values <- data.whole$analyte ##(Or in quotes
> "analyte")
> But this does not work. I've tried several other "tricks" also, but
> cannot get it to work. Can someone help?
> 
> Thanks in advance,
> 
> Jouni
> 
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