Correlation between NA columns
I have to write a function that takes a directory of data files and a threshold for complete cases and calculates the correlation between sulfate and nitrate (two columns) from each file where the number of completely observed cases (on all variables) is greater than the threshold. The function should return a vector of correlations for the monitors that meet the threshold requirement. If no files meet the threshold requirement, then the function should return a numeric vector of length 0. A prototype of this function follows My code looks like this corr <- function(directory,threshold=0){ a<