如何在r中加载和合并多个.csv文件？

Question

So I'm very new at R and right now I'm trying to load multiple .csv files (~60 or so) and then merge them together. They all have similar columns and their files are named like this: dem_file_30, dem_file_31.

I've been trying to use scripts online but keep getting some errors. I'm sure I can do it by hand but that would be really tedious.

Example:

file_list <- list.files("/home/sjclark/demographics/")   
list_of_files <- lapply(file_list, read.csv)  
m1 <- merge_all(list_of_files, all=TRUE)
Error: merge_all doesn't exist

This one seems to read them into R, but then I'm not how to do after that... help?

setwd("/home/sjclark/demographics/")
filenames <- list.files(full.names=TRUE)  
All <- lapply(filenames,function(i){
read.csv(i, header=TRUE)
})

Answer 1

It appears as if you might be trying to use the nice function shared on R-bloggers (credit to Tony Cookson) :

multMerge = function(mypath){
  filenames = list.files(path = mypath, full.names = TRUE)
  datalist = lapply(filenames, 
                    function(x){read.csv(file = x,
                                         header = TRUE,
                                         stringsAsFactors = FALSE)})
  Reduce(function(x,y) {merge(x, y, all = TRUE)}, datalist)
}

Or perhaps you have pieced things together from difference sources? In any event, merge is the crucial base R function that you were missing. merge_all doesn't exist in any package.

Since you're new to R (and maybe all programming) it's worth noting that you'll need to define this function before you use it. Once you've done that you can call it like any other function:

my_data <- multMerge("/home/sjclark/demographics/")

Answer 2

I have just been doing a very similar task and was also wondering if there is a faster/better way to do it using dplyr and bind_rows .

My code for this task is uses ldply from plyr :

library(plyr)    
filenames <- list.files(path = "mypath", pattern = "*", full.names=TRUE)
import.list <- ldply(filenames, read.csv)

Hope that helps

Rory