Question

我非常接近完成这个R程序，但结果一直给我NaN。它应该在一堆csv文件中找到硝酸盐或硫酸盐的含义。有谁知道代码可能出错的地方？以下是程序说明。这似乎很自我解释，只是我有点难过。如果您需要更多详情，请告诉我。感谢

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)
}

pollutantmean = function(directory, pollutant, id = 1:332) {
            files_polm = list.files(directory, full.names = TRUE)
            dat_3 = numeric()
            for (x in id) {
                    dat_3 = rbind(dat_3, read.csv(files_polm[x]))
            }
            if (pollutant == "sulfate") {
                    sub_pol = dat_3[which(dat_3[, "sulfate"] == "sulfate"), ]
                    mean(sub_pol[, "sulfate"], na.rm = TRUE)
            }
            else if (pollutant == "nitrate") {
                    sub_pol = dat_3[which(dat_3[, "nitrate"] == "nitrate"), ]
                    mean(sub_pol[, "nitrate"], na.rm = TRUE)
            }
            else {
                    print("Try Again")
            }
    }

Answer 1

我编辑了你的代码，假设在每个.csv文件中你的＆＃34;硝酸盐＆＃34;或＆＃34; sulafte＆＃34;列包含数字或整数数据类型，即每种物质的量/浓度。

我还修改了for循环，使其与.csv文件结构更加一致。这是代码，希望它有效 - 如果没有，请编辑以隐藏您的.csv文件的str()函数的输出

pollutantmean = function(directory, pollutant, id = 1:332) {
 files_polm = list.files(directory, full.names = TRUE)
 dat_3 = numeric()
 for (x in id) {
   if (x==id[1]) {
     dat_3 = read.csv(files_polm[x])
   } else{
     dat_3 = rbind(dat_3, read.csv(files_polm[x])) 
   }

 }
 if (pollutant == "sulfate") {
    mean(sub_pol[, "sulfate"], na.rm = TRUE)
 } else if (pollutant == "nitrate") {
    mean(sub_pol[, "nitrate"], na.rm = TRUE)
 } else {
    print("Try Again")
 }
}

R代码 - Pollutant Mean产生NaNs

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