Pfthb

I am a beginner in R. I am actually trying to code my first function.

I am looking for csv files in a directory on my computer, then I put them into a data frame and then I am asking for the mean of some variable.

I have 2 variable : sulfate and nitrate.

My function works fine for nitrate but not for sulfate. I really don't know what is wrong. R studio gave me a clue : In mean.default(directory$suftate, na.rm = TRUE) :

argument is not numeric or logical: returning NA

But I don't know what to do with this information.

My function is :

 pollutantmean <- function (directory, polluant = "nitrate", id = 1:332)
 directory <- data.frame()
 for (i in id)
directory <- rbind(directory, read.csv(full_files[i])) 
if (polluant == "nitrate")
mean(directory$nitrate,na.rm = TRUE) 
else if (polluant == "sulfate")
mean(directory$suftate,na.rm = TRUE)
else print("KO")
}

Can you help me ?

Caroline

1. An opening curly brace is missing in the very first line


2. This function will only work if there exists a global variable called full_files; consider passing it to
   the function explicitly


3. Likely a typo in the else if clause: directory$sulfate, not directory$suftate
   


4. This function does not return anything; executing it won't actually do anything. Well, technically,
   running mean() prints some output, but it may not always be the case, especially when run from the
   command line, or when called from another function or script. Consider wrapping mean() in print() (or, even better, returning it, which will allow you to assign the mean to other variables)