[R] Choosing a column for analysis in a function

[Junnila, Jouni]

Thank you for the tip.
I already got a tip from Steve Ellison and it works for me. I'm now
using

data.whole$Analyte.Values <- data.whole[[analyte]] 

and everything goes smoothly! 
I tested also your suggestion, but got the following 
error:   "attempt to apply non-function"
So I'm sticking with Steve's suggestion. Thanks anyway!!

-Jouni

-----Original Message-----
From: Adaikalavan Ramasamy [mailto:ramasamy at cancer.org.uk] 
Sent: 31. toukokuuta 2007 16:57
To: Junnila, Jouni
Cc: r-help at stat.math.ethz.ch
Subject: Re: [R] Choosing a column for analysis in a function

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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