调试：UseMethod（“ mean”）

Question

在R Studio中使用均值函数时遇到问题。

下面是我的代码。

# Pollutant mean

pollutantmean <- function(directory, pollutant, id = 1:332) 
{
  sum_nitrate = 0
  sum_sulphate = 0
  print(directory)
  print(pollutant)
  print(id)
  file.names <- dir(directory, pattern=".csv")
  for ( i in id)
  {
     infile <- paste(directory, "/", file.names[i], sep="")
     print(infile)
     df1 <- read.csv(infile, header = TRUE)
     sum_nitrate = sum_nitrate + mean(df1$nitrate, trim=0.1, na.rm=TRUE)
   }
  }

我在使用时遇到问题，请帮帮我。