导入和读取多个文件R.

Question

I have numerous tab delimited .txtfiles named as " abcd001.txt, abcd002.txt" .... stored in a directory. I was able to import them using the following code, (whereby default directory is sames as data files directory). Its three column, all numeric type data

filenames <- list.files(path=".",pattern="abcd+.*txt")

#list of data in R
names <-substr(filenames,1,6)


for(i in names){
    filepath <- file.path(".",paste(i,".txt",sep=","))
    assign(i, read.table(filepath,
     colClasses=c("numeric"),
    sep = "\t"))
}

The code itself hasnt returned any error. My doubt is How can I access data which is being loaded? How to access say the data of the file abcd011.txt which should be three column data

The commands:names[3] just returns the file number 000002 But no data.

The code here is similar to one here: Read multiple CSV files into separate data frames .

Answer 1

I would recommend to put the results of read.table either in a list, or in one bit data.frame. In addition, I would recommend using apply style loops here, either standard R ( lapply ) or plyr . I prefer using plyr , so my examples will be using that package. An example:

## Read into a list of files:
filenames <- list.files(path=".",pattern="abcd+.*txt")
list_of_data = llply(filenames, read.table, 
                                        colClasses = c("numeric"), sep = "\t")

Accessing the data can now be done using:

list_of_data[[1]]
list_of_data[["abcd1.txt"]]

Or you could read the contents of the files into one big data.frame :

big_data = ldply(filenames, read.table, 
                             colClasses = c("numeric"), sep = "\t"))

Accessing the contents of a file can now be done using:

big_data[big_data$variable == "abcd1.txt",]