[R] Function to tabulate t-test (1) How can I get dependent variable name (2) How can I make data frame know to function

[Rui Barradas]

I've just realized that you're swapping female and male in the creation 
of the results data frame.
It should be

Table2 <- function(formula, data) {
     dname <- rownames(attr(terms(formula), "factors"))[1]
     temp <- t.test(formula, data)
     mydf <- data.frame(dep=temp$data.name,
              female=temp$estimate[2], male=temp$estimate[1],
              p=temp$p.value,
              CILow=temp$conf.int[1],CIHigh=temp$conf.int[2])
     row.names(mydf) <- NULL
     mydf
}


Rui Barradas

Em 07-01-2013 15:39, Rui Barradas escreveu:
> Hello,
>
> A simple change to your function partly answers to both questions.
>
>
> Table2 <- function(formula, data) {
>       temp <- t.test(formula, data)
>       mydf <- data.frame(dep=temp$data.name,
>                female=temp$estimate[1],male=temp$estimate[2],
>                p=temp$p.value,
>                CILow=temp$conf.int[1],CIHigh=temp$conf.int[2])
>       row.names(mydf) <- NULL
>       mydf
> }
> Table2(value ~ sex, data)
>
>
> If you want the outcome variable to be called just "value", inside the
> function use
>
> dname <- rownames(attr(terms(formula), "factors"))[1]
> mydf <- data.frame(dep=dname, [...etc...]
>
>
> Hope this helps,
>
> Rui Barradas
>
>
> Em 07-01-2013 14:44, John Sorkin escreveu:
>> Windows 7
>> R 2.12.1
>> I am trying to write a function (see sample code below) that will take the output of a t-test and produce results suitable for a table.
>> I have two questions
>> (1) You will note that the name of the outcome variable, which is "value" in the input is replaced by the string "outcome by class" in the data frame produced by my function. How can I make my function put the name of the variable being analyzed,, i.e "value" in the output data frame
>> (2) How can I pass the entire input data to the function so my call to the function will not have to be in its current ugly form, i.e.
>> Table1(data$value,data$sex)
>> and instead could just be
>> Table1(value,sex,data=data)
>>    
>>    
>> x <- data.frame(value=rnorm(20)  ,sex=rep("Male",  20))
>> y <- data.frame(value=rnorm(20,4),sex=rep("Female",20))
>> data <- rbind(x,y)
>> temp <- t.test(value~sex,data=data)
>> temp
>> v<-data.frame(dep=temp$data.name,
>>              female=temp$estimate[1],male=temp$estimate[2],
>>              p=temp$p.value,
>>              CILow=temp$conf.int[1],CIHigh=temp$conf.int[2])
>> row.names(v) <- NULL
>>    
>>    
>>    
>> Table1 <- function(outcome,class) {
>> temp <- t.test(outcome~ class)
>> mydf <- data.frame(dep=temp$data.name,
>>                female=temp$estimate[1],male=temp$estimate[2],
>>                p=temp$p.value,
>>                CILow=temp$conf.int[1],CIHigh=temp$conf.int[2])
>> row.names(mydf) <- NULL
>> mydf}
>> Table1(data$value,data$sex)
>>    
>>    
>>    
>> Thank you,
>> John
>>    
>>    
>>    
>> John David Sorkin M.D., Ph.D.
>> Chief, Biostatistics and Informatics
>> University of Maryland School of Medicine Division of Gerontology
>> Baltimore VA Medical Center
>> 10 North Greene Street
>> GRECC (BT/18/GR)
>> Baltimore, MD 21201-1524
>> (Phone) 410-605-7119
>> (Fax) 410-605-7913 (Please call phone number above prior to faxing)
>> Confidentiality Statement:
>> This email message, including any attachments, is for ...{{dropped:13}}
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