Corr1.R

corr1 <- function(directory, threshold = 0) {
        ## 'directory' is a character vector of length 1 indicating the location of
        ## the CSV files
        
        ## 'threshold' is a numeric vector of length 1 indicating the number of
        ## completely observed observations (on all variables) required to compute
        ## the correlation between nitrate and sulfate; the default is 0
        
        ## Return a numeric vector of correlations
        df = complete(directory)
        ids = df[df["nobs"] > threshold, ]$id
        corrr = numeric()
        for (i in ids) {
                
                newRead = read.csv(paste(directory, "/", formatC(i, width = 3, flag = "0"), 
                                         ".csv", sep = ""))
                dff = newRead[complete.cases(newRead), ]
                corrr = c(corrr, cor(dff$sulfate, dff$nitrate))
        }
        return(corrr)
}