R import multiple csv files

问题

I want to import multiple TSV Files (yes: TSV) in R.

Reading a single file with an selection of spacific columns works well by using:

data00<-read.csv(file = '/Volumes/2018/06_abteilungen/bi/analytics/tools/adobe/adobe_analytics/adobe_analytics_api_rohdaten/api_via_data_feed_auf_ftp/beispiel_datenexporte_data_feed/01sssamsung4de_20180501-000000.tsv',
                 sep ="\t",
             fill = TRUE,
             quote='', 
             header = FALSE 
)[ ,c(287, 288, 289, 290, 291, 292, 293, 304, 370, 661, 662, 812, 813,     994, 995, 1002)]

Now i want to import multiple files and combine them to a single dataframe:

setwd('/Volumes/2018/06_abteilungen/bi/analytics/tools/adobe/adobe_analytics/adobe_analytics_api_rohdaten/api_via_data_feed_auf_ftp/beispiel_datenexporte_data_feed/import_r')

temp <- list.files(pattern="*.tsv")

test_data <- lapply(temp, read.csv,
sep ="\t",
fill = TRUE,
quote='', 
header = FALSE 
)[ ,c(287, 288, 289, 290, 291, 292, 293, 304, 370, 661, 662, 812, 813, 994, 995, 1002)]

Last querie gives my an exception and doesnt work: Fehler in lapply(temp, read.csv, sep = "\t", fill = TRUE, quote = "", header = FALSE)[, : falsche Anzahl von Dimensionen (translation: wrong count of dimensions)

When I take all columns, it works:

test_data <- lapply(temp, read.csv,
sep ="\t",
fill = TRUE,
quote='', 
header = FALSE 
)

回答1:

You are indexing the list of data frames, and not the dataframes themselves. Try:

test_data <- lapply(temp,function(x){
  read.csv(file = x,
                 sep ="\t",
                 fill = TRUE,
                 quote='', 
                 header = FALSE 
  )[ ,c(287, 288, 289, 290, 291, 292, 293, 304, 370, 661, 662, 812, 813,994, 995, 1002)]
}
)

回答2:

Hard to say without sample-data, but I believe you have to 'merge' your imported lists first:

dplyr solution:

library(dplyr)
test_data <- lapply(temp, read.csv,
                    sep ="\t",
                    fill = TRUE,
                    quote='', 
                    header = FALSE 
                    ) %>%  
  bind_rows() %>%
  select( c(287, 288, 289, 290, 291, 292, 293, 304, 370, 661, 662, 812, 813, 994, 995, 1002) )

来源：https://stackoverflow.com/questions/50833931/r-import-multiple-csv-files

标签

import

lapply

read.csv