Hi Migdonio, I did try your code: # Initialize the rr variable as a list. rr <- as.list(rep(NA, nrow(ora)))
# Run the for-loop to store all the CSVs in rr. for (j in 1:nrow(ora)) { mycol <- ora[j,"fname"] mycsv <- paste0(mycol,".csv") rdcsv <- noquote(paste0("w:/project/_Joe.B/Oracle/data/", mycsv)) rr[[j]] <- read.csv(rdcsv) } this code is working, but rr is not a data frame, R said: Large list ( 20 elements .....). how can I use it as a data frame one by one? Thank you for your help Kai On Friday, July 9, 2021, 11:39:59 AM PDT, Migdonio González <migdonio.gonzale...@gmail.com> wrote: It seems that your problem is that you are using single quotes inside of the double quotes. This is not necessary. Here is the corrected for-loop: for (j in 1:nrow(ora)) { mycol <- ora[j,"fname"] mycsv <- paste0(mycol,".csv") rdcsv <- noquote(paste0("w:/project/_Joe.B/Oracle/data/", mycsv)) rr <- read.csv(rdcsv) } Also note that the rr variable will only store the last CSV, not all CSV. You will need to initialize the rr variable as a list to store all CSVs if that is what you require. Something like this: # Initialize the rr variable as a list. rr <- as.list(rep(NA, nrow(ora))) # Run the for-loop to store all the CSVs in rr. for (j in 1:nrow(ora)) { mycol <- ora[j,"fname"] mycsv <- paste0(mycol,".csv") rdcsv <- noquote(paste0("w:/project/_Joe.B/Oracle/data/", mycsv)) rr[[j]] <- read.csv(rdcsv) } RegardsMigdonio G. On Fri, Jul 9, 2021 at 1:10 PM Kai Yang via R-help <r-help@r-project.org> wrote: Hello List, I use for loop to read csv difference file into data frame rr. The data frame rr will be deleted after a comparison and go to the next csv file. Below is my code: for (j in 1:nrow(ora)) { mycol <- ora[j,"fname"] mycsv <- paste0(mycol,".csv'") rdcsv <- noquote(paste0("'w:/project/_Joe.B/Oracle/data/", mycsv)) rr <- read.csv(rdcsv) } but when I run this code, I got error message below: Error in file(file, "rt") : cannot open the connection In addition: Warning message: In file(file, "rt") : cannot open file ''w:/project/_Joe.B/Oracle/data/ASSAY_DEFINITIONS.csv'': No such file or directory so, I checked the rdcsv and print it out, see below: [1] 'w:/project/_Joe.B/Oracle/data/ASSAY_DEFINITIONS.csv' [1] 'w:/project/_Joe.B/Oracle/data/ASSAY_DISCRETE_VALUES.csv' [1] 'w:/project/_Joe.B/Oracle/data/ASSAY_QUESTIONS.csv' [1] 'w:/project/_Joe.B/Oracle/data/ASSAY_RUNS.csv' [1] 'w:/project/_Joe.B/Oracle/data/DATA_ENTRY_PAGES.csv' [1] 'w:/project/_Joe.B/Oracle/data/DISCRETE_VALUES.csv' [1] 'w:/project/_Joe.B/Oracle/data/ENTRY_GROUPS.csv' [1] 'w:/project/_Joe.B/Oracle/data/GEMD_CODELIST_GROUPS.csv' [1] 'w:/project/_Joe.B/Oracle/data/GEMD_CODELIST_VALUES.csv' [1] 'w:/project/_Joe.B/Oracle/data/GEMD_LOT_DEFINITIONS.csv' [1] 'w:/project/_Joe.B/Oracle/data/GEMD_SAMPLES.csv' [1] 'w:/project/_Joe.B/Oracle/data/MOLECULAR_WAREHOUSE.csv' [1] 'w:/project/_Joe.B/Oracle/data/QUESTION_DEFINITIONS.csv' [1] 'w:/project/_Joe.B/Oracle/data/QUESTION_GROUPS.csv' [1] 'w:/project/_Joe.B/Oracle/data/RESPONDENTS.csv' [1] 'w:/project/_Joe.B/Oracle/data/RESPONSES.csv' [1] 'w:/project/_Joe.B/Oracle/data/SAMPLE_LIST.csv' [1] 'w:/project/_Joe.B/Oracle/data/SAMPLE_LIST_NAMES.csv' [1] 'w:/project/_Joe.B/Oracle/data/SAMPLE_PLATE_ADDRESSES.csv' [1] 'w:/project/_Joe.B/Oracle/data/STORAGE_UNITS.csv' it seems correct. I copy and paste it into a code : rr <- read.csv( 'w:/project/_Joe.B/Oracle/data/RESPONDENTS.csv') and it works fine. Can someone help me debug where is the problem in my for loop code? Thanks, Kai [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.