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pollutantmean.R
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pollutantmean.R
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pollutantmean <- function(directory, pollutant, id = 1:332) {
## 'directory' is a character vector of length 1 indicating
## the location of the CSV files
## 'pollutant' is a character vector of length 1 indicating
## the name of the pollutant for which we will calculate the
## mean; either "sulfate" or "nitrate".
## 'id' is an integer vector indicating the monitor ID numbers
## to be used
## Return the mean of the pollutant across all monitors list
## in the 'id' vector (ignoring NA values)
filenames <- paste(formatC(id, width=3, format="d", flag="0"), ".csv", sep = "")
data <- NULL
for(filename in filenames) {
data <- rbind(data, read.csv(paste(directory, filename, sep = "/")))
}
pollutantmean <- mean(data[[pollutant]], na.rm = TRUE)
pollutantmean
}