[R] Looping multiple output values to dataframe

[Levi Waldron]

Stropharia wrote:
> # ----------------------------------------START
> R-CODE-----------------------------------
> filenames <- Sys.glob("/Users/Desktop/Test/*.csv")  # get names of files to
> process # use * to get all
>
> variables <- data.frame(1:length(filenames)) # preallocate assuming multiple
> values from each file # creates a dataframe with the same length of rows as
> the number of .csv files to process
>
> for (i in seq_along(filenames)){
>     input <- read.csv(filenames[i], header=TRUE, na.strings="NA")  
>     data.frame("input")
> 	attach(input)
> 	
> result.A <- x[2]*y[1]
> result.B <- y[2]-x[1]
> result.C <- x[3]+y[1]
>
> results <- c(result.A, result.B, result.C) # concatenate result vectors
>
> variables[i] <- results
> } 
>
> variables <- as.data.frame(t(as.matrix(variables))) # turn result vectors
> into a matrix, then transpose it and output as a data frame
>
> # add column and row names
> c.names <- c("ResultA", "ResultB", "ResultC") # set names for result vectors
> colnames(variables) <- c.names
> rownames(variables) <- filenames
>
> # export to csv file
> write.csv(variables, file="/Users/Desktop/Test.csv") 
> # ----------------------------------------END
> R-CODE-----------------------------------
>   
I think something like this should work better:

docalc <- function(thisfile){
    input <- read.csv(filenames[i], header=TRUE, na.strings="NA")
    attach(input)
    result.A <- x[2]*y[1]
    result.B <- y[2]-x[1]
    result.C <- x[3]+y[1]
    results <- c(result.A, result.B, result.C) # concatenate result vectors
    names(results) <- c("ResultA", "ResultB", "ResultC")     return(results)
}

variables <- sapply(filenames,docalc)

-- 
Levi Waldron
post-doctoral fellow
Jurisica Lab, Ontario Cancer Institute
Division of Signaling Biology
IBM Life Sciences Discovery Centre
TMDT 9-304D
101 College Street
Toronto, Ontario M5G 1L7
(416)581-7453