CODEWITHSUNDEEP
rloops
Shaxi Liver
Shaxi Liver

Reputation: 1120

Looping over few csv files by specific name

I am curious if it's possible to do such loop. I'm not so familiar with looping so please let me know if I can do it and how to do it.

I have few csv files stored in a:

    > tbl
 [1] "F1.csv"             "F10.csv"            "F11.csv"            "F12.csv"           
 [5] "F13.csv"            "F14.csv"            "F15.csv"            "F16.csv"           
 [9] "F17.csv"            "F18.csv"            "F19.csv"            "F2.csv"            
[13] "F20.csv"            "F3.csv"             "F4.csv"             "F5.csv"            
[17] "F6.csv"             "F7.csv"             "F8.csv"             "F9.csv"

That's how one of those files look like:

http://imageshack.com/a/img132/1524/w5a5.jpg

All of them are very similar. Look at the columns which I marked with red "1".

Than I created an empty matrix where I would like to keep all of the important data from all of those csv files:

## Create an empty matrix for EOD
name_cols <- paste0("F", rep(1:20, each = 4), "_", 1:4)
name_columns <- c("Description", name_cols)

mat_master_EOD <- matrix(0, nrow = length(data_rd[,1]),ncol = 81)
colnames(mat_master_EOD) <- name_columns
rownames(mat_master_EOD) <- data_rd[,1]

## Create an empty matrix for EON
name_cols <- paste0("F", rep(1:20, each = 4), "_", 1:4)
name_columns <- c("Description", name_cols)

mat_master_EON <- matrix(0, nrow = length(data_rd[,1]),ncol = 81)
colnames(mat_master_EON) <- name_columns
rownames(mat_master_EON) <- data_rd[,1]

That's how it looks like:

http://imageshack.com/a/img854/5193/u85m.jpg

Now, we can come back to the first picture and marked cells. I'd like to put the data from the F1.csv file by the "Accession".

That's what I am expecting to get:

http://imageshack.com/a/img41/1015/dcm6.jpg

So, what happened ? The data from the columns J-M from the F1.csv files were moved to the new created matrix called mat_master_EOD to columns C-F (named F1_1, F1_2, etc).

As you see I put a lot of effort to write that post. Please let me know how it should be done. What's my goal ?

To keep all of the important data for me in one csv file.

Upvotes: 0

Views: 78

Answers (1)

Zbynek
Zbynek

Reputation: 5955

There seems to be several questions you want to answer. I will answer the one in the title - looping over files.

There is convenient function 'list.files'

# list all files in d:/temp starting with 'test'
list.files('d:/temp/', pattern='^test.')
[1] "test1.dbf"    "test1.shp"    "test1.shx"    "testfile.csv" "testfile.dat" "testfile.txt"

In your case it would be:

filelist <- list.files(path, pattern='^F\d+\.csv')

Than you can loop over those filenames and do whatever you want (read.csv(filelist[1]) etc.)

for (filename in filelist){
  tempdata <- read.csv(filename)
  # perform some action with the data
}

Upvotes: 1

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