R_Programming_Assignment_1.R

pollutantmean <- function(directory, pollutant, id) {
  currentdir <- getwd()
    if (currentdir != ~directory){
      setwd(~directory) ## returns Error in setwd(directory): cannot change working directory
    }
  monitorinfo <-read.csv(id)## takes id and reads that .CSV file
  ## will monitorinfo work if given a sequence e.g, 1:10?
  pollutantcol <- monitorinfo[,pollutant]
  pollutantcolnoNAs <- pollutantcol[!is.na(pollutantcol)] ## gets rid of NAs
  meanpol <- mean(pollutantcolnoNAs)
  meanpol
}

complete <- function(directory, id){
  currentdir <- getwd()
  if (currentdir != ~directory){
    setwd(~directory) ## returns Error in setwd(directory): cannot change working directory
  }
  comdata <- data.frame(id,nobs)
  for (i in id) {
    indfile <- read.csv(id)
    occurs <- length(indfile[,1])## gets the number of occurences ie rows from indfile
    df_id_nobs <- data.frame(id,occurs)
    merge(comdata,df_id_nobs) ## want to add a row to comdata w the label id and value occurs
  comdata
  }
}

corr <- function(directory, threshold = 0) {
  currentdir <- getwd()
  if (currentdir != ~directory){
    setwd(~directory) ## returns Error in setwd(directory): cannot change working directory
  }
  cor_vector <- c()
  for (i in 332) ## 332 is the number of CSV files in the directory; better way to do this?
    obs <- read.csv(i)
    obs_noNas <- obs[!is.na(obs),1:3] ## want this to get rid of any row w/ a NA; obs should have 3 columms
    if (length(obs_noNas[,1]) >= threshold)
        {
          cor_sul_nit <- cor(obs_noNas[,2],obs_noNas[,3])
          cor_vector <- append(cor_vector,cor_sul_nit)
    }
  cor_vector
}