如何将相关应用于指定的向量，迭代文件列表？

Question

我需要获取一个dataframes列表，并将cor()应用于每个列中的相同两个列，并返回一个相关值列表。到目前为止，我的职能如下：

 corr <- function(directory, threshold = 0){

 #reads directory of files

         file_list <- list.files(path = "C:/Users/jonah/Documents/R work/R Coursera Course/specdata")



 # takes file_list and makes each file into dataframe

         dflist <- lapply(file_list, read.csv)



 # returns list of files, na rows stripped

         nolist <- lapply(dflist, na.omit)

 # removes all with nrows < threshold

         abovelist <- nolist[sapply(nolist, function(x) nrow(x) > threshold)]

          

 # runs correlation of nitrate, sulfate on remaining
         correlations <- lapply(abovelist, cor(abovelist$sulfate, abovelist$nitrate))

 }

每个dataframes有四列:日期、硫酸盐数量、硝酸盐数量和ID列。我只关心硫酸盐和硝酸盐(以及它们之间的相关性)。如何设置来处理这些列？

提前谢谢你。

每一个

Answer 1

您可以在lapply中使用匿名函数来引用对象，就像对sapply一样。

试试这个：

corr <- function(directory, threshold = 0){
  file_list <- list.files(path = directory)
  dflist <- lapply(file_list, function(x) na.omit(read.csv(x)))
  abovelist <- dflist[sapply(dflist, nrow) > threshold]
  correlations <- lapply(abovelist, function(x) cor(x$sulfate, x$nitrate))
  return(correlations)
}

并称之为：

corr("C:/Users/jonah/Documents/R work/R Coursera Course/specdata")